Python网络编程基础笔记-查询邮件大小的限制

# -*- coding:cp936 -*-
#!/usr/bin/env python
import sys,smtplib
"""
使用smtp.sina.com作为邮件发送服务器
"""
server = "smtp.sina.com"
fromaddr= "[email protected]"
toaddr = "[email protected]"

msg = """
to:%s
from:%s
Hello,I am smtp server
""" %(toaddr,fromaddr)

s = smtplib.SMTP(server)
# 进行认证，通过后可以发送邮件
s.login("jcodeer","邮箱密码")
"""
ehlo返回值：
code:来自服务器的相应码。
string:这个响应码所对应的字符串描述。
"""
code = s.ehlo()[0]
usesesmtp = 1
if not (200 <= code <= 299):
    usesesmtp = 0
    """
    code和string与ehlo含义相同。
    """
    code = s.helo()[0]
    if not (200 <= code <= 299):
        raise SMTPHeloError(code,resp)
if usesesmtp and s.has_extn("size"):
    print "Maximum message size is",s.esmtp_features["size"]
    if len(msg) > int(s.esmtp_features["size"]):
        print "Message too large;aborting."
        sys.exit(2)
s.sendmail(fromaddr,toaddr,msg)