Python smtplib发邮件时input输入参数导致邮件头显示异常

• 所有通过input()交互获取的字符串、readlines()读取的收件人地址，默认会携带首尾空白、末尾换行符等不可见字符，这些字符被写入邮件头字段（发件人、收件人、主题）后，会破坏邮件头的标准结构，导致客户端解析字段异常
• 端口号通过input()获取到的是字符串类型，而smtplib.SMTP的port参数要求传入整型，类型不匹配也会引发传输过程的异常，间接导致邮件字段显示错误
• 未对输入内容做合法性校验，非法格式的邮箱地址、包含控制字符的主题，都会导致邮件头解析失败

1. 所有输入获取的参数都调用strip()方法清除首尾不可见字符，端口号显式转为整型：

import smtplib
import getpass
from email.message import EmailMessage

fileMail = input("\nEnter the file : ").strip()
sub = input("\nEnter email subject : ").strip()
smtpServer = input("\nEnter smtp server address : ").strip()
# 端口转整型
smtpPort = int(input("\nEnter smtp port number : ").strip())
myEmail = input("\n\nEnter your Email address : ").strip()
myEmailPasswd = getpass.getpass()

try:
    mailContent = input("\nEnter email content (Please enter the ^C to end) :")
    while 1:
        mailContent += "\n" + input(">")
except KeyboardInterrupt:
    print("\n\n")

with open(fileMail, "r") as f:
    for emailAddr in f.readlines():
        # 清除收件人地址的换行与空白，过滤空行
        emailAddr = emailAddr.strip()
        if not emailAddr:
            continue
        email = EmailMessage()
        email['from'] = myEmail
        email['to'] = emailAddr
        email['subject'] = sub
        email.set_content(mailContent)
        with smtplib.SMTP(host=smtpServer, port=smtpPort) as smtp:
            smtp.ehlo()
            smtp.starttls()
            smtp.login(myEmail, myEmailPasswd)
            smtp.send_message(email)
            print(f'\n[✔️]Email was sent => {emailAddr}')

2. 如果主题包含中文或特殊符号，可显式指定编码避免乱码：

from email.header import Header
email['subject'] = Header(sub, 'utf-8')

3. 可增加简单的参数校验逻辑，比如用正则判断邮箱地址格式是否合法，避免无效参数传入。

内容的提问来源于stack exchange，提问作者Fsociety Jocker2