I quite commonly see undelivered mail to [email protected]
on the outgoing mail queue. (DSNs and out-of-office replies with empty senders - so not critical mail.)
(The Twitter mail is recieved by en25.com
/eloqua.net
which is infrastructure for "Oracle Eloqua Marketing Cloud".)
This isn’t a new issue, but I thought I’d drop a note in public about it.
If I run exim4 -v -M
on a delivery attempt I can see that it disconnects immediately after attempting to establish a STARTTLS session, so falls back to retrying without TLS.
SMTP<< 220 P01SNJ018.eloqua.net Microsoft ESMTP MAIL Service, Version: 10.0.14393.4169 ready at Tue, 10 Jan 2023 05:50:33 -0500