Meta ignores RFC 2920; ZuckMail can't send mail to servers running OpenSMTPD (opens in new tab)

(marc.info)

35 pointspghatedphones9mo ago9 comments

9 comments

Not supporting pipelining is a somewhat effective low effort spam filter. Spammers don't have time to wait for response codes, just blast the message and move on to the next sucker.

AnotherGoodName9mo ago

Above thread created 2 days ago but also isn’t this a broader bug? I was getting no emails on gmail either fwiw (wanted a recovery code, never got the email).

Let’s just wait and see for this one. I do not think it’s OpenSMTPD specific. The reply there is not from Meta, its from OpenSMTPD saying the bug is on Metas side. Which i think is true. I think they might have a major issue which has nothing to do with OpenSMTPD, Metas mail servers are just failing all round.

Bender9mo ago

Indeed it appears to be a long running broader bug [1] of 7 years. Perhaps someone could increase log and header verbosity or enable some form of debugging to see what behavior WhatsApp is invoking. It appears this [2] is how to enable debugging in OpenSMTPD. Once enabled one could trigger an email through WhatsApp to see specifically what it doing. I am nosy and curious enough that I hope someone posts the debug output here after sensitive stuff is redacted. I do not have a WhatsApp account.

[1] - https://unix.stackexchange.com/questions/392729/opensmtpd-pi...

[2] - https://wiki.archlinux.org/title/OpenSMTPD#Subsystem_tracing

JdeBP9mo ago

I'll see your 7 and raise you 10.

* https://github.com/OpenSMTPD/OpenSMTPD/issues/451

2 more replies

semiquaver9mo ago

There’s no evidence it’s a bug in opensmtpd, rather it’s that other SMTP clients such as WhatsApp’s mail servers are assuming support for the (non-mandatory) PIPELINING extension instead of respecting the EHLO-advertised (lack of) support.

1 more reply

eqvinox9mo ago

exim, if configured to do so (which is a reasonable initial spam barrier), will also reject mails due to this behaviour. It's sufficiently common (for spam) that I filtered it from logs to avoid junk buildup.

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