feature：新增邮箱注册登录功能

backend/app/services/email_service.py

@@ -0,0 +1,71 @@
+"""SMTP 邮件发送服务"""
+from __future__ import annotations
+
+from email.message import EmailMessage
+from typing import Optional
+
+import aiosmtplib
+
+from app.logger import get_logger
+
+logger = get_logger(__name__)
+
+
+class EmailService:
+    """系统 SMTP 邮件发送服务"""
+
+    async def send_mail(
+        self,
+        *,
+        host: str,
+        port: int,
+        username: str,
+        password: str,
+        use_tls: bool,
+        use_ssl: bool,
+        from_email: str,
+        from_name: str,
+        to_email: str,
+        subject: str,
+        text_body: str,
+        html_body: Optional[str] = None,
+    ) -> None:
+        if use_tls and use_ssl:
+            raise ValueError("SMTP 配置错误：TLS 和 SSL 不能同时启用")
+
+        message = EmailMessage()
+        message['From'] = f'{from_name} <{from_email}>' if from_name else from_email
+        message['To'] = to_email
+        message['Subject'] = subject
+        message.set_content(text_body)
+        if html_body:
+            message.add_alternative(html_body, subtype='html')
+
+        logger.info(f"[SMTP] 准备发送测试邮件到 {self._mask_email(to_email)}，服务器: {host}:{port}")
+
+        await aiosmtplib.send(
+            message,
+            hostname=host,
+            port=port,
+            username=username,
+            password=password,
+            use_tls=use_ssl,
+            start_tls=use_tls,
+            timeout=20,
+        )
+
+        logger.info(f"[SMTP] 测试邮件发送成功: {self._mask_email(to_email)}")
+
+    @staticmethod
+    def _mask_email(email: str) -> str:
+        if '@' not in email:
+            return email
+        name, domain = email.split('@', 1)
+        if len(name) <= 2:
+            masked_name = name[0] + '*'
+        else:
+            masked_name = name[0] + '*' * (len(name) - 2) + name[-1]
+        return f"{masked_name}@{domain}"
+
+
+email_service = EmailService()