diff --git a/CHANGELOG.md b/CHANGELOG.md
index 155744e..7455f33 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 
 ### Features
 
+- feat: |邮件状态| 新增可选 Mail Flags 功能，新邮件支持已读/未读状态、打开自动已读、手动切换状态、本页全部已读及按状态筛选，并为系统状态位及每地址自定义规则 Flag 预留扩展空间
 - feat: |Admin| 数据库页面新增 D1 存储容量展示，支持选择并保存 Free 或 Workers Paid 套餐，对比当前数据库大小和容量上限
 - feat: |用户系统| 用户中心新增发送邮件、与收件箱一致的可按绑定地址过滤的发件箱，以及地址管理凭证弹框；提供使用用户 JWT 的地址设置、发信权限申请、发信及发件箱 API
 
@@ -25,6 +26,7 @@
 
 ### Testing
 
+- test: |E2E| 覆盖新邮件默认未读、地址隔离、标记已读及非法 Flag 掩码校验
 - test: |E2E| 覆盖 D1 数据库大小响应、配置键隔离，以及数据库页面套餐选择的持久化与刷新恢复
 - fix: |E2E| 覆盖发信页面草稿编辑、正文格式切换及 HTML 预览
 - fix: |E2E| 覆盖用户 JWT 发信接口的地址归属、额度扣减、实际投递和发件箱操作，以及用户中心查看地址凭证、切换发件地址和按地址过滤发件箱的完整流程
diff --git a/CHANGELOG_EN.md b/CHANGELOG_EN.md
index 0d2eac3..f9398be 100644
--- a/CHANGELOG_EN.md
+++ b/CHANGELOG_EN.md
@@ -10,6 +10,7 @@
 
 ### Features
 
+- feat: |Mail State| Add optional Mail Flags with unread state for new mail, automatic read-on-open, manual state toggling, mark-current-page-read and state filters, plus reserved system/custom bits for future per-address rule assignment
 - feat: |Admin| Add D1 storage capacity details to the database page, with persistent Free and Workers Paid plan selection and a comparison between the current database size and capacity limit
 - feat: |User| Add mail composition, inbox-style sent-item filtering by bound address, and the shared address-credentials dialog to the user center, backed by User JWT APIs for address settings, send-access requests, sending, and sent-item management
 
@@ -25,6 +26,7 @@
 
 ### Testing
 
+- test: |E2E| Cover unread state on new mail, mailbox isolation, marking mail read, and invalid flag-mask validation
 - test: |E2E| Cover the D1 database-size response, config-key isolation, and persistence of the database-page plan selection across reloads
 - fix: |E2E| Cover draft editing, content-format switching, and HTML preview in the send-mail composer
 - fix: |E2E| Cover address ownership, balance decrement, delivery, and sent-item operations through the User JWT API, plus user-center credential display, sender switching, and sent-item filtering by address
diff --git a/db/2026-08-25-mail-flags.sql b/db/2026-08-25-mail-flags.sql
new file mode 100644
index 0000000..7fcff9d
--- /dev/null
+++ b/db/2026-08-25-mail-flags.sql
@@ -0,0 +1 @@
+ALTER TABLE raw_mails ADD COLUMN flags INTEGER;
diff --git a/db/schema.sql b/db/schema.sql
index 321d9bf..b7e7d9c 100644
--- a/db/schema.sql
+++ b/db/schema.sql
@@ -6,6 +6,7 @@ CREATE TABLE IF NOT EXISTS raw_mails (
     raw TEXT,
     raw_blob BLOB,
     metadata TEXT,
+    flags INTEGER NOT NULL DEFAULT 0,
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP
 );
 
diff --git a/e2e/fixtures/wrangler.toml.e2e b/e2e/fixtures/wrangler.toml.e2e
index 0756436..4f042f0 100644
--- a/e2e/fixtures/wrangler.toml.e2e
+++ b/e2e/fixtures/wrangler.toml.e2e
@@ -18,6 +18,7 @@ JWT_SECRET = "e2e-test-secret-key"
 BLACK_LIST = ""
 ENABLE_USER_CREATE_EMAIL = true
 ENABLE_USER_DELETE_EMAIL = true
+ENABLE_MAIL_FLAGS = true
 ENABLE_AUTO_REPLY = true
 DEFAULT_SEND_BALANCE = 10
 NO_LIMIT_SEND_ROLE = "case-role"
diff --git a/e2e/tests/api/mail-flags.spec.ts b/e2e/tests/api/mail-flags.spec.ts
new file mode 100644
index 0000000..eed09c7
--- /dev/null
+++ b/e2e/tests/api/mail-flags.spec.ts
@@ -0,0 +1,77 @@
+import { test, expect } from '@playwright/test';
+import {
+  WORKER_URL,
+  createTestAddress,
+  deleteAddress,
+  seedTestMail,
+} from '../../fixtures/test-helpers';
+
+test.describe('Mail Flags', () => {
+  test('new mail is unread and can be marked as read without changing other mailboxes', async ({ request }) => {
+    const first = await createTestAddress(request, 'mail-flags-first');
+    const second = await createTestAddress(request, 'mail-flags-second');
+
+    try {
+      await seedTestMail(request, first.address, { subject: 'Unread mail' });
+      const listRes = await request.get(`${WORKER_URL}/api/mails?limit=10&offset=0`, {
+        headers: { Authorization: `Bearer ${first.jwt}` },
+      });
+      expect(listRes.ok()).toBe(true);
+      const { results } = await listRes.json();
+      expect(results).toHaveLength(1);
+      expect(results[0].flags).toBe(1);
+
+      const unreadRes = await request.get(
+        `${WORKER_URL}/api/mails?limit=10&offset=0&flag=0&flag_state=set`,
+        { headers: { Authorization: `Bearer ${first.jwt}` } },
+      );
+      expect((await unreadRes.json()).results).toHaveLength(1);
+
+      const deniedRes = await request.patch(`${WORKER_URL}/api/mails/flags`, {
+        headers: { Authorization: `Bearer ${second.jwt}` },
+        data: { ids: [results[0].id], add: 0, remove: 1 },
+      });
+      expect(deniedRes.ok()).toBe(true);
+      expect((await deniedRes.json()).changes).toBe(0);
+
+      const updateRes = await request.patch(`${WORKER_URL}/api/mails/flags`, {
+        headers: { Authorization: `Bearer ${first.jwt}` },
+        data: { ids: [results[0].id], add: 0, remove: 1 },
+      });
+      expect(updateRes.ok()).toBe(true);
+      expect((await updateRes.json()).changes).toBe(1);
+
+      const updatedListRes = await request.get(`${WORKER_URL}/api/mails?limit=10&offset=0`, {
+        headers: { Authorization: `Bearer ${first.jwt}` },
+      });
+      expect((await updatedListRes.json()).results[0].flags).toBe(0);
+
+      const unreadAfterUpdateRes = await request.get(
+        `${WORKER_URL}/api/mails?limit=10&offset=0&flag=0&flag_state=set`,
+        { headers: { Authorization: `Bearer ${first.jwt}` } },
+      );
+      expect((await unreadAfterUpdateRes.json()).results).toHaveLength(0);
+    } finally {
+      await deleteAddress(request, first.jwt);
+      await deleteAddress(request, second.jwt);
+    }
+  });
+
+  test('rejects unsupported and overlapping flag masks', async ({ request }) => {
+    const { jwt } = await createTestAddress(request, 'mail-flags-invalid');
+    try {
+      for (const data of [
+        { ids: [1], add: 4, remove: 0 },
+        { ids: [1], add: 1, remove: 1 },
+      ]) {
+        const res = await request.patch(`${WORKER_URL}/api/mails/flags`, {
+          headers: { Authorization: `Bearer ${jwt}` },
+          data,
+        });
+        expect(res.status()).toBe(400);
+      }
+    } finally {
+      await deleteAddress(request, jwt);
+    }
+  });
+});
diff --git a/frontend/src/components/MailBox.vue b/frontend/src/components/MailBox.vue
index ce16d66..341a96e 100644
--- a/frontend/src/components/MailBox.vue
+++ b/frontend/src/components/MailBox.vue
@@ -8,6 +8,7 @@ import { useIsMobile } from '../utils/composables'
 import { processItem } from '../utils/email-parser'
 import { utcToLocalDate } from '../utils';
 import { buildReplyModel, buildForwardModel } from '../utils/mail-actions'
+import { MAIL_FLAGS, hasMailFlag } from '../utils/mail-flags'
 import MailContentRenderer from "./MailContentRenderer.vue";
 import AiExtractInfo from "./AiExtractInfo.vue";
 
@@ -55,9 +56,20 @@ const props = defineProps({
     default: false,
     required: false
   },
+  enableMailFlags: {
+    type: Boolean,
+    default: false,
+    required: false
+  },
+  updateMailFlags: {
+    type: Function,
+    default: () => { },
+    required: false
+  },
 })
 
 const localFilterKeyword = ref('')
+const mailFlagFilter = ref('all')
 
 const {
   isDark, mailboxSplitSize, mailListView, mailListPreviewLineClamp, indexTab, loading, useUTCDate,
@@ -94,6 +106,60 @@ const data = computed(() => {
   });
 })
 
+const isMailUnread = (mail) => {
+  return props.enableMailFlags && hasMailFlag(mail?.flags, MAIL_FLAGS.UNREAD)
+}
+
+const currentPageHasUnread = computed(() => rawData.value.some(isMailUnread))
+const mailFlagFilterOptions = computed(() => [
+  { label: t('allMail'), value: 'all' },
+  { label: t('unread'), value: 'unread' },
+  { label: t('read'), value: 'read' },
+])
+
+const setMailsUnread = async (mails, unread) => {
+  const changedMails = mails.filter(mail => isMailUnread(mail) !== unread)
+  if (changedMails.length === 0) return true
+
+  changedMails.forEach(mail => {
+    const flags = Number(mail.flags ?? 0)
+    mail.flags = unread ? flags | MAIL_FLAGS.UNREAD : flags & ~MAIL_FLAGS.UNREAD
+  })
+  try {
+    await props.updateMailFlags(
+      changedMails.map(mail => mail.id),
+      unread ? MAIL_FLAGS.UNREAD : 0,
+      unread ? 0 : MAIL_FLAGS.UNREAD
+    )
+    return true
+  } catch (error) {
+    changedMails.forEach(mail => {
+      const flags = Number(mail.flags ?? 0)
+      mail.flags = unread ? flags & ~MAIL_FLAGS.UNREAD : flags | MAIL_FLAGS.UNREAD
+    })
+    message.error(error.message || "error")
+    return false
+  }
+}
+
+const markMailsRead = async (mails) => setMailsUnread(mails, false)
+
+const toggleCurrentMailUnread = async () => {
+  if (!curMail.value) return
+  await setMailsUnread([curMail.value], !isMailUnread(curMail.value))
+}
+
+const openMail = async (mail) => {
+  curMail.value = mail
+  await markMailsRead([mail])
+}
+
+const markCurrentPageRead = async () => {
+  if (!await markMailsRead(rawData.value)) return
+  message.success(t("success"))
+  if (mailFlagFilter.value === 'unread') await refresh()
+}
+
 const canGoPrevMail = computed(() => {
   if (!curMail.value) return false
   const currentIndex = data.value.findIndex(mail => mail.id === curMail.value.id)
@@ -111,12 +177,12 @@ const prevMail = async () => {
   const currentIndex = data.value.findIndex(mail => mail.id === curMail.value.id)
 
   if (currentIndex > 0) {
-    curMail.value = data.value[currentIndex - 1]
+    await openMail(data.value[currentIndex - 1])
   } else if (page.value > 1) {
     page.value--
     await refresh()
     if (data.value.length > 0) {
-      curMail.value = data.value[data.value.length - 1]
+      await openMail(data.value[data.value.length - 1])
     }
   }
 }
@@ -126,12 +192,12 @@ const nextMail = async () => {
   const currentIndex = data.value.findIndex(mail => mail.id === curMail.value.id)
 
   if (currentIndex < data.value.length - 1) {
-    curMail.value = data.value[currentIndex + 1]
+    await openMail(data.value[currentIndex + 1])
   } else if (count.value > page.value * pageSize.value) {
     page.value++
     await refresh()
     if (data.value.length > 0) {
-      curMail.value = data.value[0]
+      await openMail(data.value[0])
     }
   }
 }
@@ -175,22 +241,24 @@ watch([page, pageSize], async ([page, pageSize], [oldPage, oldPageSize]) => {
   }
 })
 
+watch(mailFlagFilter, async () => {
+  await backFirstPageAndRefresh()
+})
+
 const refresh = async () => {
   try {
     const { results, count: totalCount } = await props.fetchMailData(
-      pageSize.value, (page.value - 1) * pageSize.value
+      pageSize.value, (page.value - 1) * pageSize.value, mailFlagFilter.value
     );
     loading.value = true;
     rawData.value = await Promise.all(results.map(async (item) => {
       item.checked = false;
       return await processItem(item);
     }));
-    if (totalCount > 0) {
-      count.value = totalCount;
-    }
+    if (page.value === 1) count.value = totalCount;
     curMail.value = null;
     if (!isMobile.value && !mailListView.value && data.value.length > 0) {
-      curMail.value = data.value[0];
+      await openMail(data.value[0]);
     }
   } catch (error) {
     message.error(error.message || "error");
@@ -215,7 +283,7 @@ const clickRow = async (row) => {
     curMail.value = null;
     return;
   }
-  curMail.value = row;
+  await openMail(row);
 };
 
 
@@ -381,6 +449,11 @@ onBeforeUnmount(() => {
           <n-button @click="backFirstPageAndRefresh" type="primary" tertiary>
             {{ t('refresh') }}
           </n-button>
+          <n-button v-if="enableMailFlags && currentPageHasUnread" @click="markCurrentPageRead" tertiary>
+            {{ t('markCurrentPageRead') }}
+          </n-button>
+          <n-select v-if="enableMailFlags" v-model:value="mailFlagFilter" :options="mailFlagFilterOptions"
+            style="width: 120px" />
           <n-input v-if="showFilterInput" v-model:value="localFilterKeyword"
             :placeholder="t('keywordQueryTip')" style="width: 200px; display: flex; align-items: center;"
             clearable />
@@ -397,12 +470,15 @@ onBeforeUnmount(() => {
           <div style="overflow: auto; min-height: 60vh; max-height: 100vh;">
             <n-list hoverable clickable>
               <n-list-item v-for="row in data" v-bind:key="row.id" @click="() => clickRow(row)"
-                :class="mailItemClass(row)">
+                :class="[mailItemClass(row), { 'mail-list-unread': isMailUnread(row) }]">
                 <template #prefix v-if="multiActionMode">
                   <n-checkbox v-model:checked="row.checked" />
                 </template>
                 <n-thing :title="row.subject">
                   <template #description>
+                    <n-tag v-if="isMailUnread(row)" type="warning">
+                      {{ t('unread') }}
+                    </n-tag>
                     <n-tag type="info">
                       ID: {{ row.id }}
                     </n-tag>
@@ -461,6 +537,7 @@ onBeforeUnmount(() => {
             style="overflow: auto; max-height: 100vh;">
             <MailContentRenderer :mail="curMail" :showEMailTo="showEMailTo"
               :enableUserDeleteEmail="enableUserDeleteEmail" :showReply="showReply" :showSaveS3="showSaveS3"
+              :enableMailFlags="enableMailFlags" :onToggleUnread="toggleCurrentMailUnread"
               :onDelete="deleteMail" :onReply="replyMail" :onForward="forwardMail" :onSaveToS3="saveToS3Proxy" />
           </n-card>
           <n-card :bordered="false" embedded class="mail-item" v-else>
@@ -475,7 +552,7 @@ onBeforeUnmount(() => {
       <div v-else class="mail-list-scroll">
         <n-list hoverable clickable>
           <n-list-item v-for="row in data" v-bind:key="row.id" @click="() => clickRow(row)"
-            :class="mailItemClass(row)">
+            :class="[mailItemClass(row), { 'mail-list-unread': isMailUnread(row) }]">
             <template #prefix v-if="multiActionMode">
               <n-checkbox v-model:checked="row.checked" />
             </template>
@@ -487,6 +564,9 @@ onBeforeUnmount(() => {
               </template>
               <template #description>
                 <div class="mail-list-meta">
+                  <n-tag v-if="isMailUnread(row)" type="warning">
+                    {{ t('unread') }}
+                  </n-tag>
                   <n-tag type="info">
                     ID: {{ row.id }}
                   </n-tag>
@@ -529,16 +609,26 @@ onBeforeUnmount(() => {
         <n-button @click="backFirstPageAndRefresh" tertiary size="small" type="primary">
           {{ t('refresh') }}
         </n-button>
+        <n-button v-if="enableMailFlags && currentPageHasUnread" @click="markCurrentPageRead" tertiary size="small">
+          {{ t('markCurrentPageRead') }}
+        </n-button>
       </n-space>
       <div v-if="showFilterInput" style="padding: 0 10px; margin-top: 8px; margin-bottom: 10px;">
         <n-input v-model:value="localFilterKeyword"
           :placeholder="t('keywordQueryTip')" size="small" clearable />
       </div>
+      <div v-if="enableMailFlags" style="padding: 0 10px; margin-bottom: 10px;">
+        <n-select v-model:value="mailFlagFilter" :options="mailFlagFilterOptions" size="small" />
+      </div>
       <div style="overflow: auto; min-height: 60vh; max-height: 100vh;">
         <n-list hoverable clickable>
-          <n-list-item v-for="row in data" v-bind:key="row.id" @click="() => clickRow(row)">
+          <n-list-item v-for="row in data" v-bind:key="row.id" @click="() => clickRow(row)"
+            :class="{ 'mail-list-unread': isMailUnread(row) }">
             <n-thing :title="row.subject">
               <template #description>
+                <n-tag v-if="isMailUnread(row)" type="warning">
+                  {{ t('unread') }}
+                </n-tag>
                 <n-tag type="info">
                   ID: {{ row.id }}
                 </n-tag>
@@ -568,6 +658,7 @@ onBeforeUnmount(() => {
             <MailContentRenderer :mail="curMail" :showEMailTo="showEMailTo"
               :enableUserDeleteEmail="enableUserDeleteEmail" :showReply="showReply" :showSaveS3="showSaveS3"
               :useUTCDate="useUTCDate" :onDelete="deleteMail" :onReply="replyMail" :onForward="forwardMail"
+              :enableMailFlags="enableMailFlags" :onToggleUnread="toggleCurrentMailUnread"
               :onSaveToS3="saveToS3Proxy" />
           </n-card>
         </n-drawer-content>
@@ -676,6 +767,10 @@ onBeforeUnmount(() => {
   min-width: 0;
 }
 
+.mail-list-unread :deep(.n-thing-header__title) {
+  font-weight: 700;
+}
+
 pre {
   white-space: pre-wrap;
   word-wrap: break-word;
diff --git a/frontend/src/components/MailContentRenderer.vue b/frontend/src/components/MailContentRenderer.vue
index 31accea..c483335 100644
--- a/frontend/src/components/MailContentRenderer.vue
+++ b/frontend/src/components/MailContentRenderer.vue
@@ -8,6 +8,7 @@ import { getDownloadEmlUrl } from '../utils/email-parser';
 import { blockRemoteContent } from '../utils/remote-content-policy';
 import { utcToLocalDate } from '../utils';
 import { useGlobalState } from '../store';
+import { MAIL_FLAGS, hasMailFlag } from '../utils/mail-flags';
 
 const { preferShowTextMail, useIframeShowMail, useUTCDate, isDark, autoLoadRemoteImages } = useGlobalState();
 
@@ -34,6 +35,10 @@ const props = defineProps({
     type: Boolean,
     default: false
   },
+  enableMailFlags: {
+    type: Boolean,
+    default: false
+  },
   // 回调函数 props
   onDelete: {
     type: Function,
@@ -50,6 +55,10 @@ const props = defineProps({
   onSaveToS3: {
     type: Function,
     default: () => { }
+  },
+  onToggleUnread: {
+    type: Function,
+    default: () => { }
   }
 });
 
@@ -146,6 +155,10 @@ const handleSaveToS3 = async (filename, blob) => {
         {{ t('downloadMail') }}
       </n-button>
 
+      <n-button v-if="enableMailFlags" size="small" tertiary type="info" @click="onToggleUnread">
+        {{ hasMailFlag(mail.flags, MAIL_FLAGS.UNREAD) ? t('markRead') : t('markUnread') }}
+      </n-button>
+
       <n-button v-if="showReply" size="small" tertiary type="info" @click="handleReply">
         <template #icon>
           <n-icon :component="ReplyFilled" />
diff --git a/frontend/src/i18n/message-registry.ts b/frontend/src/i18n/message-registry.ts
index 2668416..5cccda0 100644
--- a/frontend/src/i18n/message-registry.ts
+++ b/frontend/src/i18n/message-registry.ts
@@ -34,6 +34,10 @@ export const MESSAGE_REGISTRY = {
     }
   },
   "components.MailBox": {
+    "allMail": {
+      "en": "All Mail",
+      "zh": "全部邮件"
+    },
     "attachments": {
       "en": "Show Attachments",
       "zh": "查看附件"
@@ -74,6 +78,10 @@ export const MESSAGE_REGISTRY = {
       "en": "Filter current page",
       "zh": "过滤当前页"
     },
+    "markCurrentPageRead": {
+      "en": "Mark This Page as Read",
+      "zh": "本页全部已读"
+    },
     "multiAction": {
       "en": "Multi Action",
       "zh": "多选"
@@ -94,6 +102,10 @@ export const MESSAGE_REGISTRY = {
       "en": "Query",
       "zh": "查询"
     },
+    "read": {
+      "en": "Read",
+      "zh": "已读"
+    },
     "refresh": {
       "en": "Refresh",
       "zh": "刷新"
@@ -129,6 +141,10 @@ export const MESSAGE_REGISTRY = {
     "unselectAll": {
       "en": "Unselect All",
       "zh": "取消全选"
+    },
+    "unread": {
+      "en": "Unread",
+      "zh": "未读"
     }
   },
   "components.AiExtractInfo": {
@@ -194,6 +210,14 @@ export const MESSAGE_REGISTRY = {
       "en": "Load Images",
       "zh": "加载图片"
     },
+    "markRead": {
+      "en": "Mark as Read",
+      "zh": "标记已读"
+    },
+    "markUnread": {
+      "en": "Mark as Unread",
+      "zh": "标记未读"
+    },
     "remoteImagesBlocked": {
       "en": "{count} remote resources blocked to protect your privacy",
       "zh": "已阻止 {count} 项外部资源以保护隐私"
diff --git a/frontend/src/store/index.js b/frontend/src/store/index.js
index c61b195..0825782 100644
--- a/frontend/src/store/index.js
+++ b/frontend/src/store/index.js
@@ -24,6 +24,7 @@ export const useGlobalState = createGlobalState(
             disableAnonymousUserCreateEmail: false,
             disableCustomAddressName: false,
             enableUserDeleteEmail: false,
+            enableMailFlags: false,
             enableAutoReply: false,
             enableIndexAbout: false,
             /** @type {string[]} */
diff --git a/frontend/src/utils/mail-flags.js b/frontend/src/utils/mail-flags.js
new file mode 100644
index 0000000..264e435
--- /dev/null
+++ b/frontend/src/utils/mail-flags.js
@@ -0,0 +1,13 @@
+export const MAIL_FLAGS = {
+  UNREAD: 1,
+}
+
+export const hasMailFlag = (flags, flag) => {
+  return (Number(flags ?? 0) & flag) !== 0
+}
+
+export const getMailFlagFilterQuery = (filter) => {
+  if (filter === 'unread') return '&flag=0&flag_state=set'
+  if (filter === 'read') return '&flag=0&flag_state=unset'
+  return ''
+}
diff --git a/frontend/src/views/Index.vue b/frontend/src/views/Index.vue
index 00aebe1..652894a 100644
--- a/frontend/src/views/Index.vue
+++ b/frontend/src/views/Index.vue
@@ -6,6 +6,7 @@ import { useRoute } from 'vue-router'
 import { useGlobalState } from '../store'
 import { api } from '../api'
 import { useIsMobile } from '../utils/composables'
+import { getMailFlagFilterQuery } from '../utils/mail-flags'
 import { FullscreenExitOutlined } from '@vicons/material'
 
 import AddressBar from './index/AddressBar.vue';
@@ -32,19 +33,28 @@ const SendMail = defineAsyncComponent(() => {
 
 const { t } = useScopedI18n('views.Index')
 
-const fetchMailData = async (limit, offset) => {
+const fetchMailData = async (limit, offset, mailFlagFilter = 'all') => {
   if (mailIdQuery.value > 0) {
     const singleMail = await api.fetch(`/api/mail/${mailIdQuery.value}`);
     if (singleMail) return { results: [singleMail], count: 1 };
     return { results: [], count: 0 };
   }
-  return await api.fetch(`/api/mails?limit=${limit}&offset=${offset}`);
+  return await api.fetch(
+    `/api/mails?limit=${limit}&offset=${offset}${getMailFlagFilterQuery(mailFlagFilter)}`
+  );
 };
 
 const deleteMail = async (curMailId) => {
   await api.fetch(`/api/mails/${curMailId}`, { method: 'DELETE' });
 };
 
+const updateMailFlags = async (ids, add, remove) => {
+  await api.fetch(`/api/mails/flags`, {
+    method: 'PATCH',
+    body: JSON.stringify({ ids, add, remove })
+  });
+};
+
 const deleteSenboxMail = async (curMailId) => {
   await api.fetch(`/api/sendbox/${curMailId}`, { method: 'DELETE' });
 };
@@ -127,7 +137,8 @@ onMounted(() => {
           </div>
           <MailBox :key="mailBoxKey" :showEMailTo="false" :showReply="openSettings.enableSendMail" :showSaveS3="openSettings.isS3Enabled"
             :saveToS3="saveToS3" :enableUserDeleteEmail="openSettings.enableUserDeleteEmail"
-            :fetchMailData="fetchMailData" :deleteMail="deleteMail" :showFilterInput="true" />
+            :fetchMailData="fetchMailData" :deleteMail="deleteMail" :showFilterInput="true"
+            :enableMailFlags="openSettings.enableMailFlags" :updateMailFlags="updateMailFlags" />
         </n-tab-pane>
         <n-tab-pane v-if="openSettings.enableSendMail" name="sendbox" :tab="t('sendbox')">
           <SendBox :fetchMailData="fetchSenboxData" :enableUserDeleteEmail="openSettings.enableUserDeleteEmail"
diff --git a/frontend/src/views/index/SimpleIndex.vue b/frontend/src/views/index/SimpleIndex.vue
index 02db1ff..2f3b322 100644
--- a/frontend/src/views/index/SimpleIndex.vue
+++ b/frontend/src/views/index/SimpleIndex.vue
@@ -18,6 +18,7 @@ import AccountSettings from './AccountSettings.vue'
 import { processItem } from '../../utils/email-parser'
 import MailContentRenderer from '../../components/MailContentRenderer.vue'
 import AddressSelect from '../../components/AddressSelect.vue'
+import { MAIL_FLAGS, hasMailFlag } from '../../utils/mail-flags'
 
 const { jwt, settings, useSimpleIndex, showAddressCredential, openSettings, loading } = useGlobalState()
 const message = useMessage()
@@ -50,12 +51,42 @@ const fetchMails = async () => {
         totalCount.value = count > 0 ? count : totalCount.value;
         const rawMail = results && results.length > 0 ? results[0] : null
         currentMail.value = rawMail ? await processItem(rawMail) : null
+        if (openSettings.value.enableMailFlags && hasMailFlag(rawMail?.flags, MAIL_FLAGS.UNREAD)) {
+            rawMail.flags = Number(rawMail.flags ?? 0) & ~MAIL_FLAGS.UNREAD
+            await api.fetch(`/api/mails/flags`, {
+                method: 'PATCH',
+                body: JSON.stringify({ ids: [rawMail.id], add: 0, remove: MAIL_FLAGS.UNREAD })
+            })
+        }
     } catch (error) {
         console.error('Failed to fetch mails:', error)
         message.error('获取邮件失败')
     }
 }
 
+const toggleCurrentMailUnread = async () => {
+    if (!currentMail.value || !openSettings.value.enableMailFlags) return
+    const wasUnread = hasMailFlag(currentMail.value.flags, MAIL_FLAGS.UNREAD)
+    currentMail.value.flags = wasUnread
+        ? Number(currentMail.value.flags ?? 0) & ~MAIL_FLAGS.UNREAD
+        : Number(currentMail.value.flags ?? 0) | MAIL_FLAGS.UNREAD
+    try {
+        await api.fetch(`/api/mails/flags`, {
+            method: 'PATCH',
+            body: JSON.stringify({
+                ids: [currentMail.value.id],
+                add: wasUnread ? 0 : MAIL_FLAGS.UNREAD,
+                remove: wasUnread ? MAIL_FLAGS.UNREAD : 0,
+            })
+        })
+    } catch (error) {
+        currentMail.value.flags = wasUnread
+            ? Number(currentMail.value.flags ?? 0) | MAIL_FLAGS.UNREAD
+            : Number(currentMail.value.flags ?? 0) & ~MAIL_FLAGS.UNREAD
+        message.error(error.message || 'error')
+    }
+}
+
 // 删除邮件
 const deleteMail = async () => {
     if (!currentMail.value) return;
@@ -220,6 +251,7 @@ onBeforeUnmount(() => {
                     <div style="margin-top: 16px;">
                         <MailContentRenderer :mail="currentMail" :showEMailTo="false" :showReply="false"
                             :enableUserDeleteEmail="openSettings.enableUserDeleteEmail" :showSaveS3="false"
+                            :enableMailFlags="openSettings.enableMailFlags" :onToggleUnread="toggleCurrentMailUnread"
                             :onDelete="deleteMail" />
                     </div>
                 </div>
diff --git a/frontend/src/views/user/UserMailBox.vue b/frontend/src/views/user/UserMailBox.vue
index 40aea5e..5b28223 100644
--- a/frontend/src/views/user/UserMailBox.vue
+++ b/frontend/src/views/user/UserMailBox.vue
@@ -5,6 +5,7 @@ import { useScopedI18n } from '@/i18n/app'
 import { api } from '../../api'
 import { useGlobalState } from '../../store'
 import MailBox from '../../components/MailBox.vue';
+import { getMailFlagFilterQuery } from '../../utils/mail-flags';
 
 const message = useMessage()
 const { openSettings } = useGlobalState()
@@ -20,11 +21,12 @@ const queryMail = () => {
     mailBoxKey.value = Date.now();
 }
 
-const fetchMailData = async (limit, offset) => {
+const fetchMailData = async (limit, offset, mailFlagFilter = 'all') => {
     return await api.fetch(
         `/user_api/mails`
         + `?limit=${limit}`
         + `&offset=${offset}`
+        + getMailFlagFilterQuery(mailFlagFilter)
         + (addressFilter.value ? `&address=${addressFilter.value}` : '')
     );
 }
@@ -50,6 +52,13 @@ const deleteMail = async (curMailId) => {
     await api.fetch(`/user_api/mails/${curMailId}`, { method: 'DELETE' });
 };
 
+const updateMailFlags = async (ids, add, remove) => {
+    await api.fetch(`/user_api/mails/flags`, {
+        method: 'PATCH',
+        body: JSON.stringify({ ids, add, remove })
+    });
+};
+
 watch(addressFilter, async (newValue) => {
     queryMail();
 });
@@ -70,6 +79,7 @@ onMounted(() => {
         </n-input-group>
         <div style="margin-top: 10px;"></div>
         <MailBox :key="mailBoxKey" :enableUserDeleteEmail="openSettings.enableUserDeleteEmail" :fetchMailData="fetchMailData"
-            :deleteMail="deleteMail" :showFilterInput="true" />
+            :deleteMail="deleteMail" :showFilterInput="true" :enableMailFlags="openSettings.enableMailFlags"
+            :updateMailFlags="updateMailFlags" />
     </div>
 </template>
diff --git a/vitepress-docs/docs/en/guide/feature/mail-api.md b/vitepress-docs/docs/en/guide/feature/mail-api.md
index 8204dcd..400f2f5 100644
--- a/vitepress-docs/docs/en/guide/feature/mail-api.md
+++ b/vitepress-docs/docs/en/guide/feature/mail-api.md
@@ -19,6 +19,30 @@ res = requests.get(
 
 **Note**: `/api/mails` returns raw RFC822 data by design (for example `source`/`raw`), and it does not guarantee parsed fields such as `subject`, `text`, or `html`. Parse the raw source on the client side (for example with `mail-parser-wasm` or `postal-mime`) if you need readable message content.
 
+## Mail Flags API
+
+After enabling `ENABLE_MAIL_FLAGS` and running the database migration, each mail response includes an integer `flags` bitmask. Bit 0 currently means `UNREAD`: `1` is unread, while `NULL` or `0` is treated as read.
+
+With an Address JWT, use `PATCH /api/mails/flags` to add or remove flags for up to 100 mail IDs. Only the `UNREAD` bit is currently mutable.
+
+```python
+requests.patch(
+    "https://<your-worker-address>/api/mails/flags",
+    headers={"Authorization": f"Bearer {your-JWT-password}"},
+    json={"ids": [1, 2], "add": 0, "remove": 1}
+)
+```
+
+With a User JWT, send the same body to `PATCH /user_api/mails/flags`. Only mail belonging to addresses bound to that user can be changed. Other flag bits are always preserved.
+
+Mail-list endpoints accept generic flag filters: `flag` is the bit position (`0-30`), and `flag_state` is either `set` or `unset`. For example, list unread mail with:
+
+```text
+GET /api/mails?limit=20&offset=0&flag=0&flag_state=set
+```
+
+Use `flag=0&flag_state=unset` for read mail. `/user_api/mails` accepts the same parameters, and future custom flags can use bits 10 through 19 directly.
+
 ## Admin Mail API
 
 Supports `address` filter
diff --git a/vitepress-docs/docs/en/guide/worker-vars.md b/vitepress-docs/docs/en/guide/worker-vars.md
index 9fc89e8..8f59349 100644
--- a/vitepress-docs/docs/en/guide/worker-vars.md
+++ b/vitepress-docs/docs/en/guide/worker-vars.md
@@ -102,6 +102,7 @@
 | `REMOVE_EXCEED_SIZE_ATTACHMENT` | Text/JSON | If attachment exceeds 2MB, remove it, email may lose some information due to parsing                                   | `true`                     |
 | `REMOVE_ALL_ATTACHMENT`         | Text/JSON | Remove all attachments, email may lose some information due to parsing                                                 | `true`                     |
 | `ENABLE_MAIL_GZIP`             | Text/JSON | When enabled, new emails are gzip-compressed and stored in `raw_blob` column to save D1 database space. Existing plaintext `raw` data is automatically compatible for reading. **Run database migration first (`Admin -> Quick Setup -> Database -> Migrate Database` or `POST /admin/db_migration`) to ensure the `raw_blob` column exists before enabling. This feature adds compression/decompression CPU overhead, so enabling it on a paid Cloudflare Worker plan is recommended.** | `true`                     |
+| `ENABLE_MAIL_FLAGS`            | Text/JSON | Enables per-message state in the web inbox. New mail starts unread and can be opened to mark read, toggled manually, filtered by state, or marked read for the current page. Historical `NULL`/`0` values are treated as read. **Run the database migration first so `raw_mails.flags` exists before enabling this option.** | `true`                     |
 | `CLEANUP_BATCH_SIZE`           | Number    | Per-run limit for mail, sent-mail, and creation/activity-based address cleanup. Defaults to `3000`, valid range `1-5000`. Smaller values reduce per-run D1 pressure; larger values clear backlogs faster | `3000` |
 
 > [!NOTE]
diff --git a/vitepress-docs/docs/zh/guide/feature/mail-api.md b/vitepress-docs/docs/zh/guide/feature/mail-api.md
index 675a0fc..9534851 100644
--- a/vitepress-docs/docs/zh/guide/feature/mail-api.md
+++ b/vitepress-docs/docs/zh/guide/feature/mail-api.md
@@ -19,6 +19,30 @@ res = requests.get(
 
 **注意**：`/api/mails` 按设计返回的是原始 RFC822 数据（如 `source`/`raw`），不保证直接包含 `subject`、`text`、`html` 等已解析字段。若要直接读取正文，请在客户端侧解析 `raw`（例如 `mail-parser-wasm`、`postal-mime`）。
 
+## 邮件 Flag API
+
+启用 `ENABLE_MAIL_FLAGS` 并完成数据库迁移后，邮件响应中的 `flags` 为整数位掩码。当前 bit 0 表示 `UNREAD`：值为 `1` 时未读，`NULL` 或 `0` 按已读处理。
+
+地址 JWT 使用 `PATCH /api/mails/flags` 批量增删状态位。每次最多传入 100 个邮件 ID；当前仅允许修改 `UNREAD` 位。
+
+```python
+requests.patch(
+    "https://<你的worker地址>/api/mails/flags",
+    headers={"Authorization": f"Bearer {你的JWT密码}"},
+    json={"ids": [1, 2], "add": 0, "remove": 1}
+)
+```
+
+用户 JWT 使用相同请求体访问 `PATCH /user_api/mails/flags`，只能修改该用户已绑定地址的邮件。服务端始终保留请求未涉及的其他 Flag 位。
+
+邮件列表接口支持通用 Flag 查询参数：`flag` 为 bit 位置（`0-30`），`flag_state` 为 `set` 或 `unset`。例如查询未读邮件：
+
+```text
+GET /api/mails?limit=20&offset=0&flag=0&flag_state=set
+```
+
+查询已读邮件则使用 `flag=0&flag_state=unset`。`/user_api/mails` 支持相同参数，后续自定义 Flag 可以直接使用 bit 10～19。
+
 ## admin 邮件 API
 
 支持 `address` 过滤
diff --git a/vitepress-docs/docs/zh/guide/worker-vars.md b/vitepress-docs/docs/zh/guide/worker-vars.md
index b909020..7cd4cfa 100644
--- a/vitepress-docs/docs/zh/guide/worker-vars.md
+++ b/vitepress-docs/docs/zh/guide/worker-vars.md
@@ -97,6 +97,7 @@
 | `REMOVE_EXCEED_SIZE_ATTACHMENT` | 文本/JSON | 如果附件大小超过 2MB，则删除附件，邮件可能由于解析而丢失一些信息           | `true`                     |
 | `REMOVE_ALL_ATTACHMENT`         | 文本/JSON | 移除所有附件，邮件可能由于解析而丢失一些信息                               | `true`                     |
 | `ENABLE_MAIL_GZIP`             | 文本/JSON | 启用后新邮件将 Gzip 压缩存储到 `raw_blob` 字段，可节省 D1 数据库空间。已有明文 `raw` 数据自动兼容读取。**启用前请先执行数据库迁移（`Admin -> 快速设置 -> 数据库 -> 升级数据库 Schema` 或 `POST /admin/db_migration`），确保 `raw_blob` 列已创建。该功能会增加压缩/解压 CPU 开销，建议使用 Cloudflare Worker 付费 Plan 再开启。** | `true`                     |
+| `ENABLE_MAIL_FLAGS`            | 文本/JSON | 启用网页邮件状态功能。新邮件默认未读，支持打开自动已读、手动切换、按状态筛选及本页全部已读。历史邮件的 `NULL`/`0` 状态默认按已读处理。**启用前必须先执行数据库迁移，确保 `raw_mails.flags` 列已创建。** | `true`                     |
 | `CLEANUP_BATCH_SIZE`           | 数字      | 邮件、发件箱及按创建/活跃时间清理地址时的单次处理上限，默认 `3000`，有效范围 `1-5000`。较小值可降低单次 D1 压力，较大值可加快积压数据清理 | `3000` |
 
 > [!NOTE]
diff --git a/worker/src/admin_api/admin_mail_api.ts b/worker/src/admin_api/admin_mail_api.ts
index 2ac4b22..e1a846d 100644
--- a/worker/src/admin_api/admin_mail_api.ts
+++ b/worker/src/admin_api/admin_mail_api.ts
@@ -1,6 +1,8 @@
 import { Context } from "hono";
 import { handleMailListQuery } from "../common";
 import { resolveRawEmailRow } from "../gzip";
+import { serializeMailFlags } from "../mail_flags";
+import { getBooleanValue } from "../utils";
 
 export default {
     getMails: async (c: Context<HonoCustomType>) => {
@@ -31,7 +33,8 @@ export default {
             `SELECT * FROM raw_mails WHERE id = ?`
         ).bind(id).first();
         if (!result) return c.json(null);
-        return c.json(await resolveRawEmailRow(result));
+        const resolved = await resolveRawEmailRow(result);
+        return c.json(serializeMailFlags(resolved, getBooleanValue(c.env.ENABLE_MAIL_FLAGS)));
     },
     deleteMail: async (c: Context<HonoCustomType>) => {
         const { id } = c.req.param();
diff --git a/worker/src/admin_api/db_api.ts b/worker/src/admin_api/db_api.ts
index 2add400..38ff3cb 100644
--- a/worker/src/admin_api/db_api.ts
+++ b/worker/src/admin_api/db_api.ts
@@ -11,6 +11,7 @@ CREATE TABLE IF NOT EXISTS raw_mails (
     raw TEXT,
     raw_blob BLOB,
     metadata TEXT,
+    flags INTEGER NOT NULL DEFAULT 0,
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP
 );
 
@@ -197,6 +198,17 @@ export default {
                 await c.env.DB.exec(`ALTER TABLE raw_mails ADD COLUMN raw_blob BLOB;`);
             }
         }
+        if (version && version <= "v0.0.7") {
+            const tableInfo = await c.env.DB.prepare(
+                `PRAGMA table_info(raw_mails)`
+            ).all();
+            const hasFlags = tableInfo.results?.some(
+                (col: any) => col.name === 'flags'
+            );
+            if (!hasFlags) {
+                await c.env.DB.exec(`ALTER TABLE raw_mails ADD COLUMN flags INTEGER;`);
+            }
+        }
         if (version != CONSTANTS.DB_VERSION) {
             // remove all \r and \n characters from the query string
             // split by ; and join with a ;\n
diff --git a/worker/src/admin_api/worker_config.ts b/worker/src/admin_api/worker_config.ts
index cdba70b..05284b9 100644
--- a/worker/src/admin_api/worker_config.ts
+++ b/worker/src/admin_api/worker_config.ts
@@ -40,6 +40,7 @@ export default {
             "ENABLE_USER_CREATE_EMAIL": utils.getBooleanValue(c.env.ENABLE_USER_CREATE_EMAIL),
             "DISABLE_ANONYMOUS_USER_CREATE_EMAIL": utils.getBooleanValue(c.env.DISABLE_ANONYMOUS_USER_CREATE_EMAIL),
             "ENABLE_USER_DELETE_EMAIL": utils.getBooleanValue(c.env.ENABLE_USER_DELETE_EMAIL),
+            "ENABLE_MAIL_FLAGS": utils.getBooleanValue(c.env.ENABLE_MAIL_FLAGS),
             "ENABLE_AUTO_REPLY": utils.getBooleanValue(c.env.ENABLE_AUTO_REPLY),
             "COPYRIGHT": c.env.COPYRIGHT,
             "ENABLE_WEBHOOK": utils.getBooleanValue(c.env.ENABLE_WEBHOOK),
diff --git a/worker/src/commom_api.ts b/worker/src/commom_api.ts
index c8a42c9..51da126 100644
--- a/worker/src/commom_api.ts
+++ b/worker/src/commom_api.ts
@@ -39,6 +39,7 @@ api.get('/open_api/settings', async (c) => {
         "disableAnonymousUserCreateEmail": utils.getBooleanValue(c.env.DISABLE_ANONYMOUS_USER_CREATE_EMAIL),
         "disableCustomAddressName": utils.getBooleanValue(c.env.DISABLE_CUSTOM_ADDRESS_NAME),
         "enableUserDeleteEmail": utils.getBooleanValue(c.env.ENABLE_USER_DELETE_EMAIL),
+        "enableMailFlags": utils.getBooleanValue(c.env.ENABLE_MAIL_FLAGS),
         "enableAutoReply": utils.getBooleanValue(c.env.ENABLE_AUTO_REPLY),
         "enableIndexAbout": utils.getBooleanValue(c.env.ENABLE_INDEX_ABOUT),
         "copyright": c.env.COPYRIGHT,
diff --git a/worker/src/common.ts b/worker/src/common.ts
index 0fd4a49..63b6a77 100644
--- a/worker/src/common.ts
+++ b/worker/src/common.ts
@@ -7,6 +7,7 @@ import { unbindTelegramByAddress } from './telegram_api/common';
 import { CONSTANTS } from './constants';
 import { AddressCreationSettings, AdminWebhookSettings, ExtractResult, WebhookMail, WebhookSettings } from './models';
 import i18n from './i18n';
+import { serializeMailFlags } from './mail_flags';
 
 const DEFAULT_NAME_REGEX = /[^a-z0-9]/g;
 const DEFAULT_RANDOM_SUBDOMAIN_LENGTH = 8;
@@ -720,7 +721,9 @@ export const handleMailListQuery = async (
     const { results } = await c.env.DB.prepare(resultsQuery).bind(
         ...params, limit, offset
     ).all();
-    const resolvedResults = await resolveRawEmailList(results);
+    const resolvedResults = (await resolveRawEmailList(results)).map(row =>
+        serializeMailFlags(row, getBooleanValue(c.env.ENABLE_MAIL_FLAGS))
+    );
     const count = offset == 0 ? await c.env.DB.prepare(
         countQuery
     ).bind(...params).first("count") : 0;
diff --git a/worker/src/constants.ts b/worker/src/constants.ts
index 50a2a9a..ce1cf57 100644
--- a/worker/src/constants.ts
+++ b/worker/src/constants.ts
@@ -3,7 +3,7 @@ export const CONSTANTS = {
 
     // DB Version
     DB_VERSION_KEY: 'db_version',
-    DB_VERSION: "v0.0.7",
+    DB_VERSION: "v0.0.8",
 
     // DB settings
     ADDRESS_BLOCK_LIST_KEY: 'address_block_list',
diff --git a/worker/src/email/index.ts b/worker/src/email/index.ts
index e83f6f8..e3b4156 100644
--- a/worker/src/email/index.ts
+++ b/worker/src/email/index.ts
@@ -12,6 +12,7 @@ import { forwardEmail } from "./forward";
 import { EmailRuleSettings } from "../models";
 import { CONSTANTS } from "../constants";
 import { compressText } from "../gzip";
+import { insertRawMail, resolveInitialMailFlags } from "../mail_flags";
 
 
 async function email(message: ForwardableEmailMessage, env: Bindings, ctx: ExecutionContext) {
@@ -67,6 +68,9 @@ async function email(message: ForwardableEmailMessage, env: Bindings, ctx: Execu
     const message_id = message.headers.get("Message-ID");
     // save email
     try {
+        const initialFlags = await resolveInitialMailFlags(
+            getBooleanValue(env.ENABLE_MAIL_FLAGS), env, toAddress, parsedEmailContext
+        );
         let success = false;
         if (getBooleanValue(env.ENABLE_MAIL_GZIP)) {
             let compressed: ArrayBuffer | null = null;
@@ -77,38 +81,50 @@ async function email(message: ForwardableEmailMessage, env: Bindings, ctx: Execu
             }
             if (compressed) {
                 try {
-                    ({ success } = await env.DB.prepare(
-                        `INSERT INTO raw_mails (source, address, raw_blob, message_id) VALUES (?, ?, ?, ?)`
-                    ).bind(
-                        message.from, toAddress, compressed, message_id
-                    ).run());
+                    ({ success } = await insertRawMail(env.DB, {
+                        source: message.from,
+                        address: toAddress,
+                        content: compressed,
+                        contentColumn: 'raw_blob',
+                        messageId: message_id,
+                        flags: initialFlags,
+                    }));
                 } catch (dbError) {
                     // Fallback to plaintext only if raw_blob column is missing (migration not applied)
                     const errMsg = String(dbError);
                     if (errMsg.includes('raw_blob') || errMsg.includes('no such column')) {
                         console.error("raw_blob column missing, falling back to plaintext", dbError);
-                        ({ success } = await env.DB.prepare(
-                            `INSERT INTO raw_mails (source, address, raw, message_id) VALUES (?, ?, ?, ?)`
-                        ).bind(
-                            message.from, toAddress, parsedEmailContext.rawEmail, message_id
-                        ).run());
+                        ({ success } = await insertRawMail(env.DB, {
+                            source: message.from,
+                            address: toAddress,
+                            content: parsedEmailContext.rawEmail,
+                            contentColumn: 'raw',
+                            messageId: message_id,
+                            flags: initialFlags,
+                        }));
                     } else {
                         throw dbError;
                     }
                 }
             } else {
-                ({ success } = await env.DB.prepare(
-                    `INSERT INTO raw_mails (source, address, raw, message_id) VALUES (?, ?, ?, ?)`
-                ).bind(
-                    message.from, toAddress, parsedEmailContext.rawEmail, message_id
-                ).run());
+                ({ success } = await insertRawMail(env.DB, {
+                    source: message.from,
+                    address: toAddress,
+                    content: parsedEmailContext.rawEmail,
+                    contentColumn: 'raw',
+                    messageId: message_id,
+                    flags: initialFlags,
+                }));
             }
         } else {
-            ({ success } = await env.DB.prepare(
-                `INSERT INTO raw_mails (source, address, raw, message_id) VALUES (?, ?, ?, ?)`
-            ).bind(
-                message.from, toAddress, parsedEmailContext.rawEmail, message_id
-            ).run());
+            ({ success } = await insertRawMail(env.DB, {
+                source: message.from,
+                address: toAddress,
+                content: parsedEmailContext.rawEmail,
+                contentColumn: 'raw',
+                messageId: message_id,
+                flags: initialFlags,
+            }));
         }
         if (!success) {
             message.setReject(`Failed save message to ${toAddress}`);
diff --git a/worker/src/mail_flags.ts b/worker/src/mail_flags.ts
new file mode 100644
index 0000000..5db5d94
--- /dev/null
+++ b/worker/src/mail_flags.ts
@@ -0,0 +1,110 @@
+export const MAIL_FLAGS = {
+    UNREAD: 1 << 0,
+    ANSWERED: 1 << 1,
+    FLAGGED: 1 << 2,
+    DELETED: 1 << 3,
+    DRAFT: 1 << 4,
+    JUNK: 1 << 5,
+} as const;
+
+export const CUSTOM_MAIL_FLAG_OFFSET = 10;
+export const CUSTOM_MAIL_FLAG_COUNT = 10;
+export const MUTABLE_MAIL_FLAGS = MAIL_FLAGS.UNREAD;
+
+export const getCustomMailFlag = (slot: number): number => {
+    if (!Number.isInteger(slot) || slot < 0 || slot >= CUSTOM_MAIL_FLAG_COUNT) {
+        throw new Error("Invalid custom mail flag slot");
+    }
+    return 1 << (CUSTOM_MAIL_FLAG_OFFSET + slot);
+};
+
+export const serializeMailFlags = <T extends Record<string, unknown>>(
+    row: T,
+    enabled: boolean,
+): T => {
+    const result = { ...row };
+    if (!enabled) {
+        delete result.flags;
+        return result;
+    }
+    result.flags = Number(result.flags ?? 0);
+    return result;
+};
+
+export const resolveInitialMailFlags = async (
+    enabled: boolean,
+    _env: Bindings,
+    _address: string,
+    _parsedEmailContext: ParsedEmailContext,
+): Promise<number | null> => {
+    if (!enabled) return null;
+    return MAIL_FLAGS.UNREAD;
+};
+
+type InsertRawMailParams = {
+    source: string;
+    address: string;
+    content: string | ArrayBuffer;
+    contentColumn: 'raw' | 'raw_blob';
+    messageId: string | null;
+    flags: number | null;
+};
+
+export const insertRawMail = async (
+    db: D1Database,
+    params: InsertRawMailParams,
+) => {
+    const { source, address, content, contentColumn, messageId, flags } = params;
+    if (flags === null) {
+        return db.prepare(
+            `INSERT INTO raw_mails (source, address, ${contentColumn}, message_id) VALUES (?, ?, ?, ?)`
+        ).bind(source, address, content, messageId).run();
+    }
+    return db.prepare(
+        `INSERT INTO raw_mails (source, address, ${contentColumn}, message_id, flags) VALUES (?, ?, ?, ?, ?)`
+    ).bind(source, address, content, messageId, flags).run();
+};
+
+export type MailFlagUpdate = {
+    ids: number[];
+    add: number;
+    remove: number;
+};
+
+export type MailFlagFilter = {
+    mask: number;
+    state: 'set' | 'unset';
+};
+
+export const parseMailFlagFilter = (
+    bitValue: string | undefined,
+    stateValue: string | undefined,
+): MailFlagFilter | undefined | null => {
+    if (bitValue === undefined && stateValue === undefined) return undefined;
+    if (!bitValue || !/^\d+$/.test(bitValue)) return null;
+    const bit = Number(bitValue);
+    if (!Number.isInteger(bit) || bit < 0 || bit > 30) return null;
+    if (stateValue !== 'set' && stateValue !== 'unset') return null;
+    return { mask: 1 << bit, state: stateValue };
+};
+
+export const parseMailFlagUpdate = (value: unknown): MailFlagUpdate | null => {
+    if (!value || typeof value !== 'object') return null;
+    const body = value as Record<string, unknown>;
+    if (!Array.isArray(body.ids) || body.ids.length === 0 || body.ids.length > 100) return null;
+    if (body.ids.some(id => typeof id !== 'number')) return null;
+
+    const ids = [...new Set(body.ids.map(Number))];
+    if (ids.some(id => !Number.isInteger(id) || id <= 0)) return null;
+
+    if (body.add !== undefined && typeof body.add !== 'number') return null;
+    if (body.remove !== undefined && typeof body.remove !== 'number') return null;
+    const add = Number(body.add ?? 0);
+    const remove = Number(body.remove ?? 0);
+    if (!Number.isInteger(add) || !Number.isInteger(remove) || add < 0 || remove < 0) return null;
+    if (add > MUTABLE_MAIL_FLAGS || remove > MUTABLE_MAIL_FLAGS) return null;
+    if (((add | remove) & ~MUTABLE_MAIL_FLAGS) !== 0 || (add & remove) !== 0) return null;
+    if (add === 0 && remove === 0) return null;
+
+    return { ids, add, remove };
+};
diff --git a/worker/src/mails_api/index.ts b/worker/src/mails_api/index.ts
index 5373864..53bb889 100644
--- a/worker/src/mails_api/index.ts
+++ b/worker/src/mails_api/index.ts
@@ -28,6 +28,7 @@ api.post('/api/attachment/get_url', s3_attachment.getSignedGetUrl)
 // mail crud
 api.get('/api/mails', mails_crud.listMails)
 api.get('/api/mail/:mail_id', mails_crud.getMail)
+api.patch('/api/mails/flags', mails_crud.updateMailFlags)
 api.delete('/api/mails/:id', mails_crud.deleteMail)
 
 // parsed mail (server-side parsed subject/text/html/attachments)
diff --git a/worker/src/mails_api/mails_crud.ts b/worker/src/mails_api/mails_crud.ts
index 34f6525..f646580 100644
--- a/worker/src/mails_api/mails_crud.ts
+++ b/worker/src/mails_api/mails_crud.ts
@@ -5,18 +5,32 @@ import { getBooleanValue } from '../utils';
 import { handleMailListQuery, deleteAddressWithData, updateAddressUpdatedAt } from '../common'
 import { resolveRawEmailRow } from '../gzip'
 import { getSendBalanceState } from './send_balance';
+import { parseMailFlagFilter, parseMailFlagUpdate, serializeMailFlags } from '../mail_flags';
 
 const listMails = async (c: Context<HonoCustomType>) => {
     const { address } = c.get("jwtPayload")
     if (!address) {
         return c.json({ "error": "No address" }, 400)
     }
-    const { limit, offset } = c.req.query();
+    const { limit, offset, flag, flag_state } = c.req.query();
     if (Number.parseInt(offset) <= 0) updateAddressUpdatedAt(c, address);
+    const flagFilter = parseMailFlagFilter(flag, flag_state);
+    if (flagFilter === null) return c.json({ error: "Invalid mail flag filter" }, 400);
+    if (flagFilter && !getBooleanValue(c.env.ENABLE_MAIL_FLAGS)) {
+        return c.json({ error: "Mail flags are disabled" }, 403);
+    }
+
+    const filters = [`address = ?`];
+    const params = [address];
+    if (flagFilter) {
+        filters.push(`(COALESCE(flags, 0) & ?) ${flagFilter.state === 'set' ? '!=' : '='} 0`);
+        params.push(String(flagFilter.mask));
+    }
+    const whereClause = filters.join(' AND ');
     return await handleMailListQuery(c,
-        `SELECT * FROM raw_mails where address = ?`,
-        `SELECT count(*) as count FROM raw_mails where address = ?`,
-        [address], limit, offset
+        `SELECT * FROM raw_mails WHERE ${whereClause}`,
+        `SELECT count(*) as count FROM raw_mails WHERE ${whereClause}`,
+        params, limit, offset
     );
 };
 
@@ -27,7 +41,8 @@ const getMail = async (c: Context<HonoCustomType>) => {
         `SELECT * FROM raw_mails where id = ? and address = ?`
     ).bind(mail_id, address).first();
     if (!result) return c.json(null);
-    return c.json(await resolveRawEmailRow(result));
+    const resolved = await resolveRawEmailRow(result);
+    return c.json(serializeMailFlags(resolved, getBooleanValue(c.env.ENABLE_MAIL_FLAGS)));
 };
 
 const deleteMail = async (c: Context<HonoCustomType>) => {
@@ -44,6 +59,23 @@ const deleteMail = async (c: Context<HonoCustomType>) => {
     return c.json({ success });
 };
 
+const updateMailFlags = async (c: Context<HonoCustomType>) => {
+    if (!getBooleanValue(c.env.ENABLE_MAIL_FLAGS)) {
+        return c.json({ error: "Mail flags are disabled" }, 403);
+    }
+    const update = parseMailFlagUpdate(await c.req.json().catch(() => null));
+    if (!update) return c.json({ error: "Invalid mail flags request" }, 400);
+
+    const { address } = c.get("jwtPayload");
+    const placeholders = update.ids.map(() => '?').join(',');
+    const result = await c.env.DB.prepare(
+        `UPDATE raw_mails`
+        + ` SET flags = (COALESCE(flags, 0) | ?) & ~?`
+        + ` WHERE address = ? AND id IN (${placeholders})`
+    ).bind(update.add, update.remove, address, ...update.ids).run();
+    return c.json({ success: result.success, changes: result.meta.changes ?? 0 });
+};
+
 const getSettings = async (c: Context<HonoCustomType>) => {
     const { address, address_id } = c.get("jwtPayload")
     const msgs = i18n.getMessagesbyContext(c);
@@ -117,4 +149,7 @@ const clearSentItems = async (c: Context<HonoCustomType>) => {
     return c.json({ success });
 };
 
-export default { listMails, getMail, deleteMail, getSettings, deleteAddress, clearInbox, clearSentItems };
+export default {
+    listMails, getMail, deleteMail, updateMailFlags,
+    getSettings, deleteAddress, clearInbox, clearSentItems
+};
diff --git a/worker/src/mails_api/parsed_mail_api.ts b/worker/src/mails_api/parsed_mail_api.ts
index 65bd4c6..c071ea4 100644
--- a/worker/src/mails_api/parsed_mail_api.ts
+++ b/worker/src/mails_api/parsed_mail_api.ts
@@ -2,6 +2,8 @@ import { Context } from 'hono'
 
 import { commonParseMail, handleMailListQuery, updateAddressUpdatedAt } from '../common'
 import { resolveRawEmailRow } from '../gzip'
+import { serializeMailFlags } from '../mail_flags';
+import { getBooleanValue } from '../utils';
 
 const toParsedMailRow = async (row: Record<string, unknown>): Promise<Record<string, unknown>> => {
     const raw = typeof row.raw === 'string' ? row.raw : '';
@@ -46,7 +48,8 @@ const getParsedMail = async (c: Context<HonoCustomType>) => {
     ).bind(mail_id, address).first();
     if (!row) return c.json(null);
     const resolved = await resolveRawEmailRow(row);
-    return c.json(await toParsedMailRow(resolved as Record<string, unknown>));
+    const serialized = serializeMailFlags(resolved, getBooleanValue(c.env.ENABLE_MAIL_FLAGS));
+    return c.json(await toParsedMailRow(serialized));
 };
 
 export default { listParsedMails, getParsedMail };
diff --git a/worker/src/models/index.ts b/worker/src/models/index.ts
index f544393..463c499 100644
--- a/worker/src/models/index.ts
+++ b/worker/src/models/index.ts
@@ -213,6 +213,7 @@ export type RawMailRow = {
     raw?: string;
     raw_blob?: unknown;
     metadata?: string;
+    flags?: number | null;
     created_at?: string;
 }
 
diff --git a/worker/src/types.d.ts b/worker/src/types.d.ts
index ce194e8..778fa47 100644
--- a/worker/src/types.d.ts
+++ b/worker/src/types.d.ts
@@ -117,6 +117,7 @@ type Bindings = {
 
     // gzip compression for raw_mails
     ENABLE_MAIL_GZIP: string | boolean | undefined
+    ENABLE_MAIL_FLAGS: string | boolean | undefined
     CLEANUP_BATCH_SIZE: string | number | undefined
 
     // E2E testing
diff --git a/worker/src/user_api/index.ts b/worker/src/user_api/index.ts
index 6e9c458..dc6f5a4 100644
--- a/worker/src/user_api/index.ts
+++ b/worker/src/user_api/index.ts
@@ -16,6 +16,7 @@ api.get('/user_api/settings', settings.settings);
 
 // mail api
 api.get('/user_api/mails', user_mail_api.getMails);
+api.patch('/user_api/mails/flags', user_mail_api.updateMailFlags);
 api.delete('/user_api/mails/:id', user_mail_api.deleteMail);
 
 // send mail api
diff --git a/worker/src/user_api/user_mail_api.ts b/worker/src/user_api/user_mail_api.ts
index 1cf5191..ab641e0 100644
--- a/worker/src/user_api/user_mail_api.ts
+++ b/worker/src/user_api/user_mail_api.ts
@@ -2,17 +2,27 @@ import { Context } from "hono";
 import i18n from "../i18n";
 import { handleMailListQuery } from "../common";
 import { getBooleanValue } from "../utils";
+import { parseMailFlagFilter, parseMailFlagUpdate } from "../mail_flags";
 
 export default {
     getMails: async (c: Context<HonoCustomType>) => {
         const { user_id } = c.get("userPayload");
-        const { address, limit, offset } = c.req.query();
+        const { address, limit, offset, flag, flag_state } = c.req.query();
         const filterQuerys = [`ua.user_id = ?`];
         const filterParams = [String(user_id)];
         if (address) {
             filterQuerys.push(`rm.address = ?`);
             filterParams.push(address);
         }
+        const flagFilter = parseMailFlagFilter(flag, flag_state);
+        if (flagFilter === null) return c.json({ error: "Invalid mail flag filter" }, 400);
+        if (flagFilter && !getBooleanValue(c.env.ENABLE_MAIL_FLAGS)) {
+            return c.json({ error: "Mail flags are disabled" }, 403);
+        }
+        if (flagFilter) {
+            filterQuerys.push(`(COALESCE(rm.flags, 0) & ?) ${flagFilter.state === 'set' ? '!=' : '='} 0`);
+            filterParams.push(String(flagFilter.mask));
+        }
         const fromQuery = ` FROM users_address ua`
             + ` JOIN address a ON a.id = ua.address_id`
             + ` JOIN raw_mails rm ON rm.address = a.name`
@@ -41,5 +51,26 @@ export default {
         return c.json({
             success: success
         })
+    },
+    updateMailFlags: async (c: Context<HonoCustomType>) => {
+        if (!getBooleanValue(c.env.ENABLE_MAIL_FLAGS)) {
+            return c.json({ error: "Mail flags are disabled" }, 403);
+        }
+        const update = parseMailFlagUpdate(await c.req.json().catch(() => null));
+        if (!update) return c.json({ error: "Invalid mail flags request" }, 400);
+
+        const { user_id } = c.get("userPayload");
+        const placeholders = update.ids.map(() => '?').join(',');
+        const result = await c.env.DB.prepare(
+            `UPDATE raw_mails`
+            + ` SET flags = (COALESCE(flags, 0) | ?) & ~?`
+            + ` WHERE id IN (${placeholders})`
+            + ` AND EXISTS (`
+            + `SELECT 1 FROM users_address ua`
+            + ` JOIN address a ON a.id = ua.address_id`
+            + ` WHERE ua.user_id = ? AND a.name = raw_mails.address`
+            + `)`
+        ).bind(update.add, update.remove, ...update.ids, user_id).run();
+        return c.json({ success: result.success, changes: result.meta.changes ?? 0 });
     }
 }
diff --git a/worker/src/utils.ts b/worker/src/utils.ts
index 0c701d1..a3444fd 100644
--- a/worker/src/utils.ts
+++ b/worker/src/utils.ts
@@ -3,6 +3,7 @@ import { createMimeMessage } from "mimetext";
 import { UserSettings, RoleAddressConfig } from "./models";
 import { CONSTANTS } from "./constants";
 import { compressText } from "./gzip";
+import { insertRawMail, resolveInitialMailFlags } from "./mail_flags";
 
 export const getJsonObjectValue = <T = any>(
     value: string | any
@@ -371,6 +372,10 @@ export const sendAdminInternalMail = async (
         });
         const message_id = Math.random().toString(36).substring(2, 15);
         const rawText = msg.asRaw();
+        const parsedEmailContext: ParsedEmailContext = { rawEmail: rawText };
+        const initialFlags = await resolveInitialMailFlags(
+            getBooleanValue(c.env.ENABLE_MAIL_FLAGS), c.env, toMail, parsedEmailContext
+        );
         let success = false;
         if (getBooleanValue(c.env.ENABLE_MAIL_GZIP)) {
             let compressed: ArrayBuffer | null = null;
@@ -381,29 +386,49 @@ export const sendAdminInternalMail = async (
             }
             if (compressed) {
                 try {
-                    ({ success } = await c.env.DB.prepare(
-                        `INSERT INTO raw_mails (source, address, raw_blob, message_id) VALUES (?, ?, ?, ?)`
-                    ).bind("admin@internal", toMail, compressed, message_id).run());
+                    ({ success } = await insertRawMail(c.env.DB, {
+                        source: "admin@internal",
+                        address: toMail,
+                        content: compressed,
+                        contentColumn: 'raw_blob',
+                        messageId: message_id,
+                        flags: initialFlags,
+                    }));
                 } catch (dbError) {
                     const errMsg = String(dbError);
                     if (errMsg.includes('raw_blob') || errMsg.includes('no such column')) {
                         console.error("raw_blob column missing, falling back to plaintext", dbError);
-                        ({ success } = await c.env.DB.prepare(
-                            `INSERT INTO raw_mails (source, address, raw, message_id) VALUES (?, ?, ?, ?)`
-                        ).bind("admin@internal", toMail, rawText, message_id).run());
+                        ({ success } = await insertRawMail(c.env.DB, {
+                            source: "admin@internal",
+                            address: toMail,
+                            content: rawText,
+                            contentColumn: 'raw',
+                            messageId: message_id,
+                            flags: initialFlags,
+                        }));
                     } else {
                         throw dbError;
                     }
                 }
             } else {
-                ({ success } = await c.env.DB.prepare(
-                    `INSERT INTO raw_mails (source, address, raw, message_id) VALUES (?, ?, ?, ?)`
-                ).bind("admin@internal", toMail, rawText, message_id).run());
+                ({ success } = await insertRawMail(c.env.DB, {
+                    source: "admin@internal",
+                    address: toMail,
+                    content: rawText,
+                    contentColumn: 'raw',
+                    messageId: message_id,
+                    flags: initialFlags,
+                }));
             }
         } else {
-            ({ success } = await c.env.DB.prepare(
-                `INSERT INTO raw_mails (source, address, raw, message_id) VALUES (?, ?, ?, ?)`
-            ).bind("admin@internal", toMail, rawText, message_id).run());
+            ({ success } = await insertRawMail(c.env.DB, {
+                source: "admin@internal",
+                address: toMail,
+                content: rawText,
+                contentColumn: 'raw',
+                messageId: message_id,
+                flags: initialFlags,
+            }));
         }
         if (!success) {
             console.log(`Failed save message from admin@internal to ${toMail}`);
diff --git a/worker/wrangler.toml.template b/worker/wrangler.toml.template
index f57e44d..b4bc595 100644
--- a/worker/wrangler.toml.template
+++ b/worker/wrangler.toml.template
@@ -77,6 +77,8 @@ ENABLE_USER_CREATE_EMAIL = true
 # DISABLE_ANONYMOUS_USER_CREATE_EMAIL = true
 # Allow users to delete messages
 ENABLE_USER_DELETE_EMAIL = true
+# Enable per-message mail flags such as unread state. Run the database migration before enabling.
+# ENABLE_MAIL_FLAGS = true
 # Allow automatic replies to emails
 ENABLE_AUTO_REPLY = false
 # Allow webhook