On 6/28/20 6:58 AM, tom@gather.coop wrote:
Does Mailman generally send email with a null sender?
This is what I see in the log:
Jun 28 02:37:45 2020 (14588) ('127.0.0.1', 52726) handling connection Jun 28 02:37:45 2020 (14588) ('127.0.0.1', 52726) Data: b'LHLO mail.example.coop' Jun 28 02:37:45 2020 (14588) ('127.0.0.1', 52726) Data: b'MAIL FROM:<>' Jun 28 02:37:45 2020 (14588) ('127.0.0.1', 52726) sender: <> Jun 28 02:37:45 2020 (14588) ('127.0.0.1', 52726) Data: b'RCPT TO:<techque-bounces@example.org>' Jun 28 02:37:45 2020 (14588) ('127.0.0.1', 52726) recip: techque-bounces@example.org Jun 28 02:37:45 2020 (14588) ('127.0.0.1', 52726) Data: b'DATA' Jun 28 02:37:45 2020 (14588) ('127.0.0.1', 52726) Data: b'QUIT'
Notice the empty MAIL FROM.
Sendgrid seems to be choking on that because it needs to check if sending domain has been validated. If there is no sending domain it seems to reject.
Why does Mailman do this? Can it be changed? I've been trying to find the relevant section of the code to no avail.
It isn't Mailman doing this. It is the MTA at mail.example.coop that is reporting the bounce of some message from the techque@example.org list. The log messages you see are Mailman's receipt of the bounce DSN.
Bounce DSNs are always sent with a null envelope sender so if they are undeliverable, it doesn't result in another bounce. See <https://www.rfc-editor.org/rfc/rfc3461.html#section-6.1>.
-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan