cloudflare_temp_email/vitepress-docs/docs/en/guide/config-send-mail.md

Configure Email Sending

::: warning Note All three methods can be configured simultaneously. When sending emails, it will prioritize using resend, if resend is not configured, it will use smtp.

If a Cloudflare authenticated forwarding email address is configured, CF's internal API will be prioritized for sending emails :::

Send Emails Using Resend

Register at https://resend.com/domains and add DNS records according to the instructions.

Create an api key on the API KEYS page.

Then execute the following command to add RESEND_TOKEN to secrets:

Note

If you find this troublesome, you can also put it directly in plain text under [vars] in wrangler.toml, but this is not recommended

If you deployed through the UI, you can add it under Variables and Secrets in the Cloudflare UI interface.

# Switch to worker directory
cd worker
wrangler secret put RESEND_TOKEN

If you have multiple domains with different api keys, you can add multiple secrets in wrangler.toml, named RESEND_TOKEN_ + <UPPERCASE DOMAIN WITH . REPLACED BY _>, for example:

wrangler secret put RESEND_TOKEN_XXX_COM
wrangler secret put RESEND_TOKEN_DREAMHUNTER2333_XYZ

Send Emails Using SMTP

The format of SMTP_CONFIG is as follows. The key must be your own sending domain, and the value is the SMTP configuration.

For SMTP configuration format details, refer to zou-yu/worker-mailer

[!warning] Important The JSON key (e.g. your-domain.com in the example below) must be replaced with your own domain — the domain configured in your DOMAINS variable. This is one of the most common configuration mistakes. Do not copy the example domain directly.

{
    "your-domain.com": {
        "host": "smtp.example.com",
        "port": 465,
        "secure": true,
        "authType": [
            "plain",
            "login"
        ],
        "credentials": {
            "username": "your-smtp-username",
            "password": "your-smtp-password"
        }
    }
}

Field Reference:

Field	Description
key (e.g. your-domain.com)	Your sending domain, must match a domain configured in DOMAINS
host	SMTP server address, e.g. smtp.mailgun.org, smtp.gmail.com, or your self-hosted SMTP server
port	SMTP port, typically 465 (SSL) or 587 (STARTTLS)
secure	Whether to use SSL/TLS. Set to true for port 465, false for port 587
authType	Authentication method, typically ["plain", "login"]
credentials.username	SMTP server login username
credentials.password	SMTP server login password

If you have multiple domains using different SMTP services, add multiple keys in the same JSON:

{
    "domain-a.com": {
        "host": "smtp.mailgun.org",
        "port": 465,
        "secure": true,
        "authType": ["plain", "login"],
        "credentials": { "username": "user@domain-a.com", "password": "xxx" }
    },
    "domain-b.com": {
        "host": "smtp.gmail.com",
        "port": 465,
        "secure": true,
        "authType": ["plain", "login"],
        "credentials": { "username": "user@gmail.com", "password": "app-password" }
    }
}

Then execute the following command to add SMTP_CONFIG to secrets:

Note

If you find this troublesome, you can also put it directly in plain text under [vars] in wrangler.toml, but this is not recommended

If you deployed through the UI, you can add it under Variables and Secrets in the Cloudflare UI interface.

# Switch to worker directory
cd worker
wrangler secret put SMTP_CONFIG

Send Balance Mechanism

Users need a send balance to send emails. The balance mechanism works as follows:

1. Request Send Permission: Users must first click the "Request Send Permission" button in the frontend
2. Default Quota: Upon requesting, users receive the default quota set by the DEFAULT_SEND_BALANCE environment variable (defaults to 0 if not set)
3. Unlimited Sending: The following methods can bypass balance checks:
   • Add the address to the "No Limit Send Address List" in the admin console
   • Configure the NO_LIMIT_SEND_ROLE environment variable to specify roles that can send without limits

Note

DEFAULT_SEND_BALANCE does NOT automatically grant balance to all addresses. Users must actively request send permission first for the quota to take effect.

Send Emails to Authenticated Forwarding Addresses on Cloudflare

Only supported for CLI deployment, add send_email configuration in wrangler.toml.

The destination email address must be an authenticated email address on Cloudflare, which has significant limitations. If you need to send emails to other addresses, you can use resend or smtp to send emails.

# Send emails through Cloudflare
send_email = [
   { name = "SEND_MAIL" },
]

Admin console account configuration Verified address list (can send emails through CF internal API)