A number of people have been seeing an increase in AOL bounces over the last few days. Some of these are the new rejection 554/421 CON:B1 message. This is, basically, you’ve topped our thresholds, back off.
The other one is a bit more interesting. The error message a lot of people are seeing is 554/421 RLY:SN. Senders should only be getting this error message when they are sending email from a banned address.
This error indicates you are sending email using a disallowed AOL.COM screenname as your FROM or REPLY-TO address, or as one of AOL’s affiliates from an unauthorized IP address. Example: Billing@aol.com
Clearly this is AOL attempting to minimize phishing and spoofing of the AOL brand. This is a great thing.
Unfortunately, there seems to be some problems with the current implementation. This rule is catching perfectly legitimate email. One report I have seen is that mail with @aol.com in the from address is getting rejected with this message. That means all those small businesses sending mail from their @aol.com addresses through an ESP are seeing problems. Another report I’ve seen is that email addresses with “a” “o” “l” in order (like, for instance, firstname.lastname@example.org) are also getting rejections.
It’s very possible that this filter is catching other mail, too.
Folks I’ve talked to are in touch with AOL and AOL is working on fixing the issue.
Note these do seem to be intermittent errors and not every email with an @aol.com address in the from line or some rendition of “aol” in the email address is getting bounced. But if you do start seeing increases in the number of AOL bounces and they are RLY:SN, this may be why. A short term work around will probably be to modify From: addresses where possible. Longer term, we’re just going to have to wait for AOL to fix things.