https://www.runoob.com/python/python-email.html

#!/usr/bin/python
# -*- coding: UTF-8 -*-

import smtplib
from email.mime.text import MIMEText
from email.header import Header

# 第三方 SMTP 服务
mail_host="smtp.XXX.com"  #设置服务器
mail_user="XXXX"    #用户名
mail_pass="XXXXXX"   #口令 


sender = '[email protected]'
receivers = ['[email protected]']  # 接收邮件，可设置为你的QQ邮箱或者其他邮箱

message = MIMEText('Python 邮件发送测试...', 'plain', 'utf-8')
message['From'] = Header("菜鸟教程", 'utf-8')
message['To'] =  Header("测试", 'utf-8')

subject = 'Python SMTP 邮件测试'
message['Subject'] = Header(subject, 'utf-8')


try:
    smtpObj = smtplib.SMTP() 
    smtpObj.connect(mail_host, 25)    # 25 为 SMTP 端口号
    smtpObj.login(mail_user,mail_pass)  
    smtpObj.sendmail(sender, receivers, message.as_string())
    print "邮件发送成功"
except smtplib.SMTPException:
    print "Error: 无法发送邮件"

实践版本

#!/usr/bin/python
# -*- coding: UTF-8 -*-

import smtplib
from email.mime.text import MIMEText
from email.header import Header

# 第三方 SMTP 服务
mail_host = "smtp.163.com"  # 设置服务器
mail_user = "****@163.com"  # 用户名
mail_pass = "******"  # 口令

sender = '*****@163.com'
receivers = ['*****[email protected]']  # 接收邮件，可设置为你的QQ邮箱或者其他邮箱

try:
    smtpObj = smtplib.SMTP()
    smtpObj.connect(mail_host, 25)  # 25 为 SMTP 端口号  未加密
    smtpObj.login(mail_user, mail_pass)
    smtpObj.sendmail(sender, receivers, '123455667')
    print("邮件发送成功")
except smtplib.SMTPException:
    print("Error: 无法发送邮件")

import smtplib
from email.mime.text import MIMEText
from email.header import Header

import ssl

# 第三方 SMTP 服务
mail_host = "smtp.163.com"  # 设置服务器
mail_user = "******@163.com"  # 用户名
mail_pass = "******"  # 口令

sender = mail_user
receivers = ['******@qq.com']  # 接收邮件，可设置为你的QQ邮箱或者其他邮箱

try:
    context = ssl.create_default_context() #使用ssl模块的context加载系统允许的证书，在登录时进行验证
    smtpObj = smtplib.SMTP_SSL(mail_host, 465, context=context) # 完成加密通讯
    smtpObj.login(mail_user, mail_pass)
    smtpObj.sendmail(sender, receivers, '123455667')
    print("邮件发送成功")
    smtpObj.quit()
except smtplib.SMTPException:
    print("Error: 无法发送邮件")

#!/usr/bin/python
# -*- coding: UTF-8 -*-

import smtplib
from email.mime.text import MIMEText
from email.header import Header

import ssl

# 第三方 SMTP 服务
mail_host = "smtp.163.com"  # 设置服务器
mail_user = "*****@163.com"  # 用户名
mail_pass = "****"  # 口令

sender = mail_user
receivers = ['****@qq.com']  # 接收邮件，可设置为你的QQ邮箱或者其他邮箱

message = MIMEText('mainSpider Report123123132', 'plain', 'utf-8')
message['From'] = sender
subject = 'mainSpider Report'
message['Subject'] = Header(subject, 'utf-8')

try:
    context = ssl.create_default_context()  #使用ssl模块的context加载系统允许的证书，在登录时进行验证
    smtpObj = smtplib.SMTP_SSL(mail_host, 465, context=context)  # 完成加密通讯
    smtpObj.login(mail_user, mail_pass)
    for r in receivers:
        message['To'] = r
        smtpObj.send_message(message)
        # smtpObj.sendmail(message.as_string())
    print("邮件发送成功")
    smtpObj.quit()
except smtplib.SMTPException:
    print("Error: 无法发送邮件")

Python操作邮箱发送邮件（网易邮箱）
PYTHON学习笔记（31）——关于smtplib库MIMEText和MIMEMultipart类的应用之自动发送邮件（html格式，有正文，有链接，有附件）