Emails to AOL being delayed, then rejected

I'm having an odd issue with AOL that has recurred 3 times now, with 3 different AOL recipients. Each time, I've sent an email with no problem, then they reply. Then when I reply back, it's returned with this somewhat generic error: From: Mail Delivery System [[EMAIL='Mailer-Daemon@gonc02.goncinc.com">mailto:Mailer-Daemon@example.com[/EMAIL]] Sent: Saturday, November 07, 2015 9:25 PM To: me@example.com Subject: Mail delivery failed: returning message to sender This message was created automatically by mail delivery software. A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: example@aol.com host mailin-03.mx.aol.com [12.34.56.78] SMTP error from remote mail server after initial connection: 421 mtaig-mae04.mx.aol.com Service unavailable - try again later: retry timeout exceeded Reporting-MTA: dns; myserver.example.com Action: failed Final-Recipient: [EMAIL='rfc822;parkslandg@aol.com">rfc822;example@aol.com[/EMAIL] Status: 5.0.0 Remote-MTA: dns; mailin-03.mx.aol.com Diagnostic-Code: smtp; 421 mtaig-mae04.mx.aol.com Service unavailable - try again later: retry timeout exceeded
My Senderbase reputation is Neutral, and MXToolbox shows that I'm not on any blacklists. Can anyone suggest whether this issue is on my end or AOL's? Either way, is there anything I can do to fix it on my end?

cPanelMichael

November 09, 2015 02:14

Hello :) That message indicates AOL is blocking the email from your server. The first step is to verify the basic email guidelines are setup correctly on your system: How to Keep your Email out of the Spam Folder - cPanel Knowledge Base - cPanel Documentation Thank you.

GoWilkes

November 09, 2015 07:56

Hmm. Thanks, Michael. I went through all of the steps listed, and everything checks out perfectly. I've had an SPF Filter, DMARC policy, and DKIM key set up for at least a year, and running "dig" as instructed returned exactly what I thought. The only warning from MXToolbox says that Reverse DNS doesn't match the SMTP Banner. I did some research and found references to changing it at /etc/exim.conf, but it's currently the default and I have no idea what should be changed: "${primary_hostname} ESMTP Exim ${version_number} \#${compile_number} ${tod_full} \n We do not authorize the use of this system to transport unsolicited, \n and/or bulk e-mail."
Could this be the reason it's being rejected intermittently? If so, how should I edit it?

November 09, 2015 13:35

Have you verified the RDNS entry for your IP address matches the hostname of the server? Thank you.

November 09, 2015 20:36

I did, and MXToolbox confirmed it.

November 09, 2015 20:37

I don't suspect the SMTP banner notification would result in AOL blocking your email. I suggest requesting they delist you by contacting them directly: AOL Postmaster - Open a Trouble Ticket Thank you.

Emails to AOL being delayed, then rejected

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