如何在Python中发送隐藏收件人的多份邮件？

你当前代码的问题在于把所有收件人都塞进了To字段，所以每个收件人打开邮件时都能看到其他收件人的地址。要实现隐藏收件人，有两种靠谱的方法：

方法一：使用密送（Bcc）字段 #

密送字段里的收件人不会被其他收件人看到，只需调整邮件头的设置即可：

import smtplib
from email.message import EmailMessage

email_subject = "Good morning"
sender_email_address = "user@outlook.com"
receivers_email_address = ['reciever1@gmail.com', 'reciever2@gmail.com']
email_smtp = "smtp.office365.com"
email_password = "MyPassword"

# 创建邮件对象
message = EmailMessage()

# 配置邮件头
message['Subject'] = email_subject
message['From'] = sender_email_address
# 将To设为自己（或占位邮箱），避免收件人看到空的To字段
message['To'] = sender_email_address
# 用Bcc存放所有收件人，他们互相看不到对方地址
message['Bcc'] = receivers_email_address

# 读取HTML邮件内容
with open('message.html', 'r') as file:
   file_content = file.read()

# 设置HTML格式的邮件内容
message.set_content(file_content, subtype='html')

# 连接SMTP服务器
server = smtplib.SMTP(email_smtp, '587')
server.ehlo()
server.starttls()
server.login(sender_email_address, email_password)

# 发送邮件
server.send_message(message)

# 关闭连接
server.quit()

方法二：逐个单独发送邮件 #

这种方法会给每个收件人单独发送一封邮件，每封邮件的To字段只有对方自己的地址，完全避免信息泄露：

import smtplib
from email.message import EmailMessage

email_subject = "Good morning"
sender_email_address = "user@outlook.com"
receivers_email_address = ['reciever1@gmail.com', 'reciever2@gmail.com']
email_smtp = "smtp.office365.com"
email_password = "MyPassword"

# 提前读取HTML内容，避免重复打开文件
with open('message.html', 'r') as file:
   file_content = file.read()

# 连接SMTP服务器
server = smtplib.SMTP(email_smtp, '587')
server.ehlo()
server.starttls()
server.login(sender_email_address, email_password)

# 循环给每个收件人单独发邮件
for receiver in receivers_email_address:
    message = EmailMessage()
    message['Subject'] = email_subject
    message['From'] = sender_email_address
    message['To'] = receiver
    message.set_content(file_content, subtype='html')
    server.send_message(message)
    print(f"邮件已发送给 {receiver}")

# 关闭连接
server.quit()

注意事项 #

• 使用Bcc时，部分邮箱服务商可能限制单次密送的人数，若收件人数量较多，建议优先用第二种方法。
• 循环发送时不要过于频繁，避免触发邮箱的反垃圾邮件机制，必要时可添加短暂延时（如time.sleep(1)）。

内容的提问来源于stack exchange，提问作者Juan Jose Acevedo