Python3郵件發送全指南：文本、HTML與附件

在 Python3 中，使用內置的 smtplib 庫和 email 模塊發送郵件是一個常見的需求。以下是更詳細的實現指南，包含各種場景的解決方案和技術細節：

一、發送純文本郵件的完整實現

準備工作：
- 確保已開通 SMTP 服務（各郵箱開啟方式不同）
- 獲取 SMTP 授權碼（非登錄密碼）
- 確認服務器地址和端口（常見配置見下表）

郵箱服務	SMTP服務器	SSL端口	TLS端口
QQ郵箱	smtp.qq.com	465	587
163郵箱	smtp.163.com	465	994
Gmail	smtp.gmail.com	465	587

核心代碼詳解：

import smtplib
import ssl
from email.mime.text import MIMEText
from email.header import Header
from email.utils import formataddr, formatdate, make_msgid
from datetime import datetime# 增強的郵件配置
config = {"smtp_server": "smtp.examples.com","smtp_port": 465,"sender_email": "your_email@example.com","sender_name": "系統管理員",  # 發件人顯示名稱"password": "your_smtp_password","receivers": [{"email": "user1@example.com", "name": "張經理"},{"email": "user2@example.com", "name": "李主管"}]
}# 構建郵件內容（支持多行模板）
email_template = """尊敬的{recipient_name}：這是來自{system_name}的系統通知郵件。當前時間：{current_time}
系統狀態：正常運行
最近事件：
{events}請及時處理相關事務。
"""events = "\n".join(["1. 用戶登錄異常(3次)","2. 數據庫備份完成","3. 新版本發布通知"
])# 填充模板內容
email_body = email_template.format(recipient_name="各位",  # 群發時的通用稱呼system_name="OA系統",current_time=datetime.now().strftime("%Y-%m-%d %H:%M:%S"),events=events
)# 創建MIME對象
msg = MIMEText(email_body, "plain", "utf-8")# 設置郵件頭（規范格式）
msg["From"] = formataddr((config["sender_name"], config["sender_email"]))
msg["To"] = ", ".join([formataddr((r["name"], r["email"])) for r in config["receivers"]]
)
msg["Subject"] = Header("【重要】系統狀態通知", "utf-8")# 高級郵件頭設置
msg["Date"] = formatdate(localtime=True)
msg["Message-ID"] = make_msgid()
msg["X-Priority"] = "1"  # 郵件優先級(1-5, 1最高)
msg["X-Mailer"] = "Python SMTP"  # 郵件客戶端標識# 安全發送流程
context = ssl.create_default_context()
try:with smtplib.SMTP_SSL(config["smtp_server"],config["smtp_port"],context=context,timeout=10  # 設置超時時間) as server:server.login(config["sender_email"], config["password"])# 實際發送時區分密送和抄送to_addresses = [r["email"] for r in config["receivers"]]server.sendmail(config["sender_email"],to_addresses,msg.as_string())print(f"成功發送郵件至 {len(to_addresses)} 位收件人")
except smtplib.SMTPException as e:print(f"郵件發送失敗，SMTP錯誤: {str(e)}")
except Exception as e:print(f"發生未知錯誤: {str(e)}")

二、HTML郵件的專業實現

高級功能支持：
- 響應式設計（適應移動端）
- 嵌入式CSS和JavaScript
- 動態內容渲染
- 郵件跟蹤（通過嵌入圖片）
完整示例：

from email.mime.multipart import MIMEMultipart# 創建多部分郵件
msg = MIMEMultipart("alternative")
msg["From"] = formataddr(("市場部", "marketing@company.com"))
msg["To"] = "customer@example.com"# 純文本備用內容
text_part = MIMEText("這是純文本備用內容", "plain", "utf-8")# HTML主要內容
html_content = """
<!DOCTYPE html>
<html>
<head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>產品推廣郵件</title><style type="text/css">/* 響應式設計 */body { font-family: 'Helvetica Neue', Arial, sans-serif; margin: 0; padding: 0; }.container { max-width: 600px; margin: 0 auto; padding: 20px; }.header { background-color: #3498db; color: white; padding: 20px; text-align: center; }.content { padding: 20px; line-height: 1.6; }.button { display: inline-block; background: #2ecc71; color: white; padding: 10px 20px; text-decoration: none; border-radius: 5px; }.footer { color: #7f8c8d; font-size: 12px; text-align: center; padding: 20px; }@media screen and (max-width: 480px) {.container { width: 100% !important; }}</style>
</head>
<body><div class="container"><div class="header"><h1>新產品發布</h1></div><div class="content"><p>尊敬的客戶：</p><p>我們很高興向您介紹我們的最新產品...</p><p><a href="https://example.com/product" class="button">立即查看</a></p><!-- 產品特性表格 --><table border="0" cellpadding="0" cellspacing="0" width="100%"><tr><td width="50%" valign="top"><h3>核心功能</h3><ul><li>高性能處理</li><li>簡單易用</li></ul></td><td width="50%" valign="top"><h3>技術優勢</h3><ul><li>先進算法</li><li>穩定可靠</li></ul></td></tr></table><!-- 郵件跟蹤像素 --><img src="https://example.com/track?email=customer@example.com" width="1" height="1"></div><div class="footer"><p>? 2023 公司名稱. 保留所有權利.</p><p><a href="%unsubscribe_url%">退訂郵件</a></p></div></div>
</body>
</html>
"""html_part = MIMEText(html_content, "html", "utf-8")# 添加郵件部分
msg.attach(text_part)  # 注意順序：先添加純文本版本
msg.attach(html_part)# 發送邏輯同上...

三、帶附件郵件的專業實現

郵件附件的處理是郵件系統開發中的關鍵環節，需要注意以下技術要點：

自動檢測MIME類型
- 通過文件擴展名識別（如.jpg對應image/jpeg）
- 使用文件頭信息檢測（如PDF文件的%PDF標識）
- 可集成第三方庫如Apache Tika進行精確識別
- 示例：檢測到.txt文件自動設置Content-Type為text/plain
支持大文件分塊處理
- 采用BASE64編碼時注意76字符換行規則
- 實施斷點續傳機制
- 使用HTTP/1.1的chunked傳輸編碼
- 典型場景：10MB以上的視頻文件傳輸
處理中文文件名
- 必須進行RFC 2231編碼（如=?UTF-8?B?5Lit5paH?=）
- 文件名長度限制為75個字符
- 避免使用非ASCII字符的擴展名
- 示例處理流程：UTF-8編碼 → BASE64編碼 → MIME頭格式化
添加多個附件
- 每個附件作為獨立的MIME part
- 使用multipart/mixed作為頂層Content-Type
- 注意附件順序對郵件客戶端顯示的影響
- 典型實現：附件1（合同.pdf）+附件2（報價單.xlsx）
其他注意事項
- 設置正確的Content-Disposition（attachment/inline）
- 處理Windows/Linux路徑差異
- 添加附件描述信息（Content-Description頭字段）
- 安全考慮：病毒掃描和文件類型限制
完整示例：

import os
import mimetypes
from email.mime.base import MIMEBase
from email import encodersdef add_attachment(msg, filepath):"""專業添加附件方法"""if not os.path.exists(filepath):raise FileNotFoundError(f"附件文件不存在: {filepath}")# 猜測MIME類型ctype, encoding = mimetypes.guess_type(filepath)if ctype is None or encoding is not None:ctype = "application/octet-stream"maintype, subtype = ctype.split("/", 1)with open(filepath, "rb") as fp:part = MIMEBase(maintype, subtype)part.set_payload(fp.read())# 編碼和設置頭信息encoders.encode_base64(part)# 處理中文文件名filename = os.path.basename(filepath)part.add_header("Content-Disposition","attachment",filename=Header(filename, "utf-8").encode())msg.attach(part)# 創建帶附件的郵件
msg = MIMEMultipart()
msg["Subject"] = "季度報告和數據分析"# 添加正文
msg.attach(MIMEText("請查收附件中的季度報告", "plain"))# 添加多個附件
attachments = ["/reports/Q3_Report.pdf","/data/sales_data.xlsx","/images/performance_chart.png"
]for attachment in attachments:try:add_attachment(msg, attachment)print(f"已添加附件: {os.path.basename(attachment)}")except Exception as e:print(f"添加附件失敗: {str(e)}")# 發送邏輯...

四、企業級最佳實踐

連接池管理增強版

from smtplib import SMTP_SSL
from queue import Queue
import threadingclass SMTPConnectionPool:def __init__(self, host, port, username, password, pool_size=5):self.host = hostself.port = portself.username = usernameself.password = passwordself.pool = Queue(pool_size)self.lock = threading.Lock()# 初始化連接池for _ in range(pool_size):conn = SMTP_SSL(host, port)conn.login(username, password)self.pool.put(conn)def get_connection(self):return self.pool.get()def release_connection(self, conn):self.pool.put(conn)def send_email(self, msg, recipients):conn = Nonetry:conn = self.get_connection()conn.sendmail(self.username, recipients, msg.as_string())finally:if conn:self.release_connection(conn)# 使用示例
pool = SMTPConnectionPool(host="smtp.example.com",port=465,username="user@example.com",password="password",pool_size=10
)# 在多線程環境中使用
def worker(email_list):for email in email_list:msg = build_email_message(email)pool.send_email(msg, [email["address"]])threads = []
for i in range(5):t = threading.Thread(target=worker, args=(email_chunks[i],))threads.append(t)t.start()for t in threads:t.join()

完整的郵件服務類

import logging
from logging.handlers import RotatingFileHandlerclass EmailService:def __init__(self, config):self.config = configself.logger = self._setup_logger()self.connection_pool = self._init_connection_pool()def _setup_logger(self):logger = logging.getLogger("EmailService")logger.setLevel(logging.INFO)handler = RotatingFileHandler("email_service.log",maxBytes=10*1024*1024,  # 10MBbackupCount=5)formatter = logging.Formatter("%(asctime)s - %(levelname)s - %(message)s")handler.setFormatter(formatter)logger.addHandler(handler)return loggerdef _init_connection_pool(self):return SMTPConnectionPool(host=self.config["smtp_host"],port=self.config["smtp_port"],username=self.config["smtp_user"],password=self.config["smtp_password"],pool_size=self.config.get("pool_size", 5))def send_email(self, template_name, recipient, context, attachments=None):"""發送模板郵件"""try:# 1. 加載模板template = self._load_template(template_name)# 2. 構建郵件內容msg = self._build_message(template, recipient, context)# 3. 添加附件if attachments:for attachment in attachments:self._add_attachment(msg, attachment)# 4. 發送郵件self.connection_pool.send_email(msg,[recipient["email"]])self.logger.info(f"郵件發送成功: {template_name} -> {recipient['email']}")return Trueexcept Exception as e:self.logger.error(f"郵件發送失敗: {template_name} -> {recipient['email']}: {str(e)}",exc_info=True)return False# 其他輔助方法...def _load_template(self, name):"""加載郵件模板"""passdef _build_message(self, template, recipient, context):"""構建郵件消息"""passdef _add_attachment(self, msg, filepath):"""添加附件"""pass

監控與統計集成

from prometheus_client import CollectorRegistry, push_to_gateway
from datetime import datetimeclass EmailMetrics:def __init__(self):self.registry = CollectorRegistry()self.emails_sent = Counter("emails_sent_total","Total emails sent",["template"],registry=self.registry)self.send_time = Summary("email_send_time_seconds","Time spent sending emails",registry=self.registry)self.errors = Counter("email_errors_total","Total email sending errors",["type"],registry=self.registry)def record_success(self, template, duration):self.emails_sent.labels(template).inc()self.send_time.observe(duration)def record_error(self, error_type):self.errors.labels(error_type).inc()def push_metrics(self):push_to_gateway("metrics.example.com:9091",job="email_service",registry=self.registry)# 使用示例
metrics = EmailMetrics()@metrics.send_time.time()
def send_email_with_metrics(email):try:start_time = datetime.now()# 發送郵件邏輯...duration = (datetime.now() - start_time).total_seconds()metrics.record_success(email["template"], duration)return Trueexcept smtplib.SMTPException as e:metrics.record_error("smtp")raiseexcept Exception as e:metrics.record_error("other")raisefinally:metrics.push_metrics()

五、高級主題擴展

DKIM簽名支持

import dkimdef add_dkim_signature(msg, domain, selector, private_key):"""添加DKIM簽名"""headers = ["From", "To", "Subject"]sig = dkim.sign(message=msg.as_bytes(),selector=selector.encode(),domain=domain.encode(),privkey=private_key.encode(),include_headers=headers)msg["DKIM-Signature"] = sig[len("DKIM-Signature: "):].decode()return msg# 使用示例
private_key = """-----BEGIN RSA PRIVATE KEY-----
...
-----END RSA PRIVATE KEY-----"""msg = add_dkim_signature(msg,domain="example.com",selector="selector1",private_key=private_key
)

郵件隊列系統集成

import redis
import json
import pickleclass EmailQueue:def __init__(self, redis_host="localhost", redis_port=6379):self.redis = redis.Redis(host=redis_host,port=redis_port,db=0,decode_responses=False)self.queue_name = "email_queue"def enqueue(self, email_task):"""將郵件任務加入隊列"""serialized = pickle.dumps(email_task)self.redis.rpush(self.queue_name, serialized)def dequeue(self):"""從隊列取出郵件任務"""serialized = self.redis.lpop(self.queue_name)if serialized:return pickle.loads(serialized)return Nonedef process_queue(self, worker_count=4):"""處理隊列中的郵件"""def worker():while True:task = self.dequeue()if not task:breaktry:send_email(**task)except Exception as e:self._handle_failure(task, e)threads = []for _ in range(worker_count):t = threading.Thread(target=worker)threads.append(t)t.start()for t in threads:t.join()# 使用示例
queue = EmailQueue()# 生產者添加任務
queue.enqueue({"to": "user@example.com","subject": "測試郵件","body": "這是一封測試郵件","template": "welcome"
})# 消費者處理隊列
queue.process_queue()

通過這些擴展實現，可以構建出適應不同場景的完整郵件解決方案，從簡單的通知郵件到復雜的企業級郵件服務。關鍵是根據實際需求選擇合適的技術方案，并注意處理各種邊界情況和異常狀態。