docs: clarify wildcard MX requirement for random subdomain (#1036)

Random subdomain mailbox creation only generates addresses; mail delivery
depends on DNS / Cloudflare Email Routing covering *.<base-domain>.
Cloudflare Email Routing does not inherit apex configuration onto
subdomains, so a wildcard `*` MX record on the base domain is required
for random subdomains to actually receive mail.

- Add `[!IMPORTANT]` block in subdomain.md (zh/en) explaining the two
  deliverable paths: DNS-only wildcard MX (recommended for random
  subdomains) vs Cloudflare dashboard "Add subdomain"
- Link to Cloudflare Email Routing — Subdomains official docs from
  worker-vars.md and subdomain.md
- Instruct copying apex MX records to host `*` preserving each record's
  priority/target, instead of hardcoding specific MX targets
- Shorten frontend `randomSubdomainTip` for CreateAccount and Login
  views (6 locales: zh/en/de/es/ja/pt-BR), drop Markdown backticks
  (Vue text interpolation renders them literally), and point users to
  the docs instead of embedding DNS instructions
- Trim overlap between existing `[!NOTE]` and new `[!IMPORTANT]` in
  subdomain.md
- Update CHANGELOG.md / CHANGELOG_EN.md under v1.9.0(main)

Closes #1035
Closes #1026

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

vitepress-docs/docs/en/guide/feature/subdomain.md

@@ -52,9 +52,30 @@ If you want to create an address under a specific subdomain such as `team.abc.co
 >
 > There is currently no backend switch that globally forces random subdomains; API calls that do
 > not pass `enableRandomSubdomain: true` will not randomize automatically.
+
+> [!IMPORTANT] A wildcard MX DNS record is required for random subdomains
+> The worker only generates addresses like `name@<random>.abc.com` — **whether mail actually
+> arrives depends entirely on DNS / Email Routing being configured for `*.abc.com`**, and
+> Cloudflare Email Routing does **not** propagate the base-domain configuration onto subdomains.
+> See Cloudflare's [Email Routing — Subdomains](https://developers.cloudflare.com/email-routing/setup/subdomains/)
+> documentation.
 >
-> It does not automatically create Cloudflare-side subdomain mail routes or DNS records for you,
-> so make sure the base-domain/subdomain routing is already available first.
+> There are two ways to make `*.abc.com` deliverable:
+>
+> 1. **DNS-only wildcard MX (simplest workaround)** — In your DNS, copy **every existing MX
+>    record on `abc.com`** to host `*`, preserving each record's **priority and target value**.
+>    This makes `*.abc.com` resolve to the same MX targets as the apex, so mail flows into the
+>    same Cloudflare Email Routing zone and is picked up by the apex Catch-all rule that points
+>    at the Worker. No extra Cloudflare-side action is needed.
+> 2. **Cloudflare dashboard "Add subdomain"** — Add the specific subdomain in the Email Routing
+>    dashboard and configure its DNS + Catch-all routing rule separately. This only covers the
+>    specific subdomain you add, so it is not suitable for arbitrary random subdomains.
+>
+> For random subdomain mailboxes, option **(1)** is the recommended path. Without it, the
+> random subdomain feature will appear to work in the UI but inbound mail will never reach the
+> Worker.
+>
+> Reference issue: [#1035](https://github.com/dreamhunter2333/cloudflare_temp_email/issues/1035)
 
 ## Let APIs Specify Subdomains Directly
 

vitepress-docs/docs/en/guide/worker-vars.md

@@ -51,6 +51,15 @@
 > `RANDOM_SUBDOMAIN_DOMAINS` only controls automatic random subdomain generation during mailbox
 > creation. It does not create Cloudflare-side subdomain routing for you.
 >
+> To actually receive mail on addresses like `name@<random>.abc.com`, **you must add a wildcard
+> `*` MX record under the base domain in DNS** by copying the apex's existing MX records to
+> host `*` (preserving each record's priority and target). Cloudflare Email Routing does not
+> inherit the apex configuration onto subdomains — see the
+> [Cloudflare Email Routing — Subdomains](https://developers.cloudflare.com/email-routing/setup/subdomains/)
+> docs,
+> [#1035](https://github.com/dreamhunter2333/cloudflare_temp_email/issues/1035) and
+> [Configure Subdomain Email](/en/guide/feature/subdomain).
+>
 > Subdomain addresses are usually best used for receiving only; for sending, prefer the main
 > domain.
 >

vitepress-docs/docs/zh/guide/feature/subdomain.md

@@ -45,8 +45,18 @@ RANDOM_SUBDOMAIN_LENGTH = 8
 > 这个功能只是在“创建地址”时自动补一个随机二级域名。
 >
 > 当前没有“全局强制随机二级域名”的后端开关；未传 `enableRandomSubdomain: true` 的 API 调用不会自动随机。
+
+> [!IMPORTANT] 随机子域名需要 DNS 通配 MX 记录
+> 程序只负责生成 `name@<random>.abc.com` 这样的地址，**能不能收到邮件完全取决于 DNS / Email Routing 是否覆盖到 `*.abc.com`**；Cloudflare Email Routing 的子域名配置**不会**从基础域名继承。可参考 Cloudflare 的 [Email Routing — Subdomains](https://developers.cloudflare.com/email-routing/setup/subdomains/) 文档。
 >
-> 它不会自动帮你创建 Cloudflare 侧的子域名收件路由或 DNS 配置，请先确保基础域名/子域名路由本身已经可用。
+> 让 `*.abc.com` 可投递有两种做法：
+>
+> 1. **DNS 通配 MX 记录（最简方案）** — 在 `abc.com` 的 DNS 中，把基础域名上**现有的每一条 MX 记录**都复制一份到 `*` 主机名上，**保留每条记录的 priority 与 target**。这样 `*.abc.com` 会解析到与 apex 相同的 MX 目标，邮件流向同一个 Cloudflare Email Routing zone，并由 apex 的 Catch-all 规则交给 Worker，**Cloudflare 侧不需要额外配置**。
+> 2. **Cloudflare 控制台 “Add subdomain”** — 在 Email Routing 后台显式添加该子域名，并单独配置其 DNS 与 Catch-all 路由规则。这只覆盖你添加的那个具体子域名，不适合随机生成的任意子域名。
+>
+> 随机子域名场景下推荐使用 **方案 (1)**。如果不做这一步，随机子域名功能在前端看起来正常，但实际邮件不会进入 Worker。
+>
+> 参考 issue：[#1035](https://github.com/dreamhunter2333/cloudflare_temp_email/issues/1035)
 
 ## 允许 API 直接指定子域名
 

vitepress-docs/docs/zh/guide/worker-vars.md

@@ -51,6 +51,13 @@
 > `RANDOM_SUBDOMAIN_DOMAINS` 只负责“创建地址时自动补随机子域名”，不会自动帮你创建 Cloudflare
 > 侧的子域名路由。
 >
+> 要让 `name@<随机>.abc.com` 这种随机子域名地址真的能收到邮件，**必须在基础域名的 DNS 中为
+> `*` 子域添加通配 MX 记录**：把基础域名上现有的每一条 MX 记录都复制到 `*` 主机名上，
+> 并保留 priority 与 target；Email Routing 子域不继承父域配置，详见 Cloudflare 的
+> [Email Routing — Subdomains](https://developers.cloudflare.com/email-routing/setup/subdomains/)
+> 文档、[#1035](https://github.com/dreamhunter2333/cloudflare_temp_email/issues/1035) 与
+> [配置子域名邮箱](/zh/guide/feature/subdomain)。
+>
 > 子域名地址通常更适合收件；如果要发件，仍建议优先使用主域名。
 >
 > `ENABLE_CREATE_ADDRESS_SUBDOMAIN_MATCH` 与随机子域名功能不同：它允许 API 调用方**直接指定**