通过 SMTP 发送邮件

使用任意支持 SMTP 的语言或客户端，通过 Cloudflare Email Service 已认证 SMTP（smtp.mx.cloudflare.net:465）发送事务性邮件。

前提条件

已为 Email Sending 接入域名。
具有 Email Sending: Edit 权限的 Cloudflare API 令牌。请在环境中将其设为 CF_API_TOKEN。该令牌用作 SMTP 密码；用户名为字面字符串 api_token。

发送邮件

cat > mail.txt <<EOF
From: [email protected]
To: [email protected]
Subject: Welcome to our service!

Thanks for signing up.
EOF

curl --ssl-reqd \
  --url "smtps://smtp.mx.cloudflare.net:465" \
  --user "api_token:$CF_API_TOKEN" \
  --mail-from "[email protected]" \
  --mail-rcpt "[email protected]" \
  --upload-file mail.txt

发件人域名必须已在拥有该 API 令牌的账户上为 Email Sending 接入。

使用 npm install nodemailer 安装 Nodemailer ↗。

发送邮件

import nodemailer from "nodemailer";

const transporter = nodemailer.createTransport({
	host: "smtp.mx.cloudflare.net",
	port: 465,
	secure: true, // implicit TLS
	auth: {
		user: "api_token",
		pass: process.env.CF_API_TOKEN,
	},
});

const info = await transporter.sendMail({
	from: '"Acme" <[email protected]>',
	to: "[email protected]",
	subject: "Welcome to Acme",
	text: "Thanks for signing up.",
	html: "<h1>Welcome to Acme</h1><p>Thanks for signing up.</p>",
});

console.log("Message sent:", info.messageId);

发送带附件的邮件

const info = await transporter.sendMail({
	from: '"Acme Billing" <[email protected]>',
	to: "[email protected]",
	subject: "Your invoice",
	text: "Please find your invoice attached.",
	attachments: [
		{
			filename: "invoice-2026-04.pdf",
			path: "./invoices/invoice-2026-04.pdf",
			contentType: "application/pdf",
		},
	],
});

消息总大小（含 base64 编码的附件）不得超过 5 MiB。请参阅限制。

错误处理

Nodemailer 会以 Error 拒绝 promise，其 .responseCode 反映 SMTP 响应码。请参阅 SMTP 响应码与故障排除。

try {
	await transporter.sendMail({
		/* ... */
	});
} catch (err) {
	console.error(err.responseCode, err.message);
}

使用标准库 smtplib ↗（Python 3.8 或更高版本）。

发送邮件

import os
import smtplib
from email.message import EmailMessage

msg = EmailMessage()
msg["From"] = "Acme <[email protected]>"
msg["To"] = "[email protected]"
msg["Subject"] = "Welcome to Acme"
msg.set_content("Thanks for signing up.")
msg.add_alternative(
    "<h1>Welcome to Acme</h1><p>Thanks for signing up.</p>",
    subtype="html",
)

with smtplib.SMTP_SSL("smtp.mx.cloudflare.net", 465) as s:
    s.login("api_token", os.environ["CF_API_TOKEN"])
    s.send_message(msg)

smtplib.SMTP_SSL 会在端口 465 上打开隐式 TLS 连接，这是 Cloudflare SMTP 端点所要求的。请勿使用带 starttls() 的 smtplib.SMTP；不支持 STARTTLS。

发送给多个收件人

msg["To"] = ", ".join([
    "[email protected]",
    "[email protected]",
    "[email protected]",
])

单个 SMTP 会话最多可投递 50 个 RCPT TO 地址。请参阅限制。

发送带附件的邮件

from pathlib import Path

pdf = Path("invoice-2026-04.pdf").read_bytes()
msg.add_attachment(
    pdf,
    maintype="application",
    subtype="pdf",
    filename="invoice-2026-04.pdf",
)

错误处理

smtplib 会抛出 smtplib.SMTPException 的子类，并附带 SMTP 响应码。请参阅 SMTP 响应码与故障排除。

try:
    with smtplib.SMTP_SSL("smtp.mx.cloudflare.net", 465) as s:
        s.login("api_token", os.environ["CF_API_TOKEN"])
        s.send_message(msg)
except smtplib.SMTPAuthenticationError as e:
    print(f"Auth failed: {e.smtp_code} {e.smtp_error!r}")
except smtplib.SMTPResponseException as e:
    print(f"SMTP error: {e.smtp_code} {e.smtp_error!r}")

发送邮件

<?php
use PHPMailer\PHPMailer\PHPMailer;

require 'vendor/autoload.php';

$mail = new PHPMailer(true);
$mail->isSMTP();
$mail->Host       = 'smtp.mx.cloudflare.net';
$mail->Port       = 465;
$mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;
$mail->SMTPAuth   = true;
$mail->Username   = 'api_token';
$mail->Password   = getenv('CF_API_TOKEN');

$mail->setFrom('[email protected]', 'Acme');
$mail->addAddress('[email protected]');
$mail->Subject = 'Welcome to our service!';
$mail->Body    = 'Thanks for signing up.';
$mail->send();

后续步骤

SMTP 参考 — 连接详情、身份验证、响应码与故障排除。
指定收件人 — 多个收件人、CC 与 BCC，以及命名地址。
限制 — 账户、消息与会话限制。