AOL postmaster rejections.

John Peach john-nanog at
Thu Nov 19 14:08:31 UTC 2015

Has anyone else with relatively large volumes of email seen a huge
spike in rejections from AOL recently?

There is no obvious reason why they are being rejected as it is a
generic message:

Nov 18 12:10:39 pp-serve02 sendmail[1391]: tAIHAcPT001383: SMTP DATA-2 protocol error: 521 5.2.1 :  AOL
will not accept delivery of this message.

Looking back through my logs, I can see we've always had a few, but we
are now receiving a lot of complaints from users (physicians who cannot
email their patients) and I see this, starting on Monday:


and I already have 55 for today.

We have a whitelist / feedback loop set up with AOL, our IPs show clean
with them and our DNS / reverse DNS has not changed and resolves

We did raise a ticket with them, but it seems to have gone to the
usual /dev/null.

To reply off-list, please remove the VERP -nanog from my email address,
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