#coding: utf-8
import smtplib
from email.mime.text import MIMEText
from email.header import Header

sender = '[email protected]'
receiver = '[email protected]'
subject = '放假通知'
smtpserver = 'smtp.163.com'
username = ''
password = ''

msg = MIMEText('大家關好窗戶','plain','utf-8')#中文需引數‘utf-8'，單位元組字元不需要
msg['Subject'] = Header(subject, 'utf-8')
msg['From'] = 'Tim<
 
[email protected]>'  
msg['To'] = "[email protected]"
smtp = smtplib.SMTP()
smtp.connect('smtp.163.com')
smtp.login(username, password)
smtp.sendmail(sender, receiver, msg.as_string())
smtp.quit()

只賦值了msg['Subject'], 沒有賦值msg['From'], msg['To']，導致出現554情況，更改了後就好了。

注意MIMEText初始化的時候，中文的第二個引數要用'plain'，我用'text',中文就顯示不出來。

msg['From'] 中人名為Tim，會和下面對應起來。