email alerter failed to alert

[lavaplanet12]

E2021-05-01 20:14:48,832 [root] email alerter failed to alert
Traceback (most recent call last):
File "/src/alerter/common.py", line 38, in call
alerter(**kwargs)
File "/src/alerter/emailer.py", line 50, in call
msg["Subject"] = set_subject
File "/usr/local/lib/python3.9/email/message.py", line 409, in setitem
self._headers.append(self.policy.header_store_parse(name, val))
File "/usr/local/lib/python3.9/email/policy.py", line 146, in header_store_parse
raise ValueError("Header values may not contain linefeed "
ValueError: Header values may not contain linefeed or carriage return characters

[ridsama]

Have the same issue, sendmail works. Relay set to 127.0.0.1.