On 2021-09-27, Grant Edwards <grant.b.edwa...@gmail.com> wrote: > Why does SMTP.send_message(msg) do from mangling even though msg's > policy has mangle_from_ set to False? The msg policy is > email.policy.SMTP which has mangle_from_ disabled. > > One might expect that SMTP.send_message(msg) would use either msg's > policy or email.policy.SMTP to send the message, but it does neither.
I've been looking at the smtplib.py sources, and the problem appears to be in this section of send_message(): 912 def send_message(self, msg, from_addr=None, to_addrs=None, 913 mail_options=(), rcpt_options=()): 914 """Converts message to a bytestring and passes it to sendmail. ... 963 # Make a local copy so we can delete the bcc headers. 964 msg_copy = copy.copy(msg) ... 977 with io.BytesIO() as bytesmsg: 978 if international: 979 g = email.generator.BytesGenerator( 980 bytesmsg, policy=msg.policy.clone(utf8=True)) 981 mail_options = (*mail_options, 'SMTPUTF8', 'BODY=8BITMIME') 982 else: 983 g = email.generator.BytesGenerator(bytesmsg) 984 g.flatten(msg_copy, linesep='\r\n') 985 flatmsg = bytesmsg.getvalue() If 'international' is Frue, then the BytesGenerator uses msg.policy with utf8 added, and I don't get the bogus from mangling: the generator only does from mangling if the message policy has it enabled. If 'international' is False, then the generator always does from mangling regardless of the message's policy. According to https://docs.python.org/3/library/email.generator.html#email.generator.BytesGenerator the default from mangling behavior is _supposed_ to obey the message policy if (as seen at 983) no policy or mangle_from_ value was provided to the call to BytesGenerator(). In my tests, it doesn't actually seem to work that way. AFAICT, the default behavior when no policy or mangle_from_ value is passed to BytesGenerator() is to enable from mangling regardless of the message's policy. I belive that is a bug. This can be worked around by changing 983 g = email.generator.BytesGenerator(bytesmsg) to 983 g = email.generator.BytesGenerator(bytesmsg, policy=msg.policy) Or BytesGenerator() could be fixed... -- Grant -- https://mail.python.org/mailman/listinfo/python-list
