binascii.Error raised in smtplib when initial_response_ok=False

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-04-27.07:57:58.359>
labels = ['3.8', 'type-bug', '3.7', 'expert-email', '3.9']
title = 'binascii.Error raised in smtplib when initial_response_ok=False'
updated_at = <Date 2021-05-07.07:37:31.111>
user = 'https://bugs.python.org/junpengruan'

bugs.python.org fields:

activity = <Date 2021-05-07.07:37:31.111>
actor = 'junpengruan'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['email']
creation = <Date 2021-04-27.07:57:58.359>
creator = 'junpengruan'
dependencies = []
files = []
hgrepos = []
issue_num = 43949
keywords = []
message_count = 5.0
messages = ['392039', '393059', '393060', '393061', '393172']
nosy_count = 4.0
nosy_names = ['barry', 'r.david.murray', 'pepoluan', 'junpengruan']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue43949'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8', 'Python 3.9']