python通过IMAP收发邮件出错

Question

import imaplib,email,getpass
from email.utils import getaddresses

#Email settings
imap_server = 'imap.qq.com'
imap_user = '******@qq.com'
imap_password = '*******'#这里是授权码

#Connection
conn = imaplib.IMAP4_SSL(imap_server)
(retcode,capabilities) = conn.login(imap_user,imap_password)

print(conn.list())
conn.select('INBOX')

#search for ids between dates specified
result,data = conn.uid('search',None,b'(SINCE "01-Dec-2016" BEFORE "24-Dec-2016")')
uids = data[0].split()

#Download headers
result,data = conn.uid('fetch',','.join(uids), 'BODY[HEADER]')

错误提示如下