关于smtplib中有个MIMEMultipart的设置问题

[yuanalexwu]

首先这个发送的是html格式的邮件
--------------------------------

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText


msg = MIMIMultipart('alternative')
msg_root['Subject'] = 'Greating'
msg_root['From'] = 'bro <[e-mail]>'
msg_root['To'] = '<[e-mail]>'
msg_root.set_boundary() # 这里如何设置这个边界
part1 = MIMEText(text_content, 'plain', 'UTF-8')
part2 = MIMEText(html_content, 'html', 'UTF-8')
msg_root.attach(part1)
msg_root.attach(part2)


-------------------------------
上面代码中的set_boundary() 一般情况下设置什么?