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Do Linode IP have trouble with AOL? (421 DYN:T1 block)
https://forum.linode.com/viewtopic.php?f=11&t=9174		 Page 1 of 1
Author:  QuantumMechanic [ Sun Jul 22, 2012 12:53 am ]
Post subject:  Do Linode IP have trouble with AOL? (421 DYN:T1 block)
I've migrated a mailman mailing list from a physical server to my Linode server. On the physical server I have never had any problems with AOL blocking mails from the list and AOL's IP address reputation check says the physical machine's IP address's reputation is good.

However, now that I'm on Linode, I'm getting AOL's 421 DYN:T1 block and my Linode's IP address reputation is "undisclosed". I have reverse resolution set up consistently (the MX host resolves to an IP address that reverse-resolves to the MX host) and I have SPF and DKIM set up. I have verified (by adding my gmail address to the mailing list membership) that SPF and DKIM are set up properly, since gmail is showing both the SPF and DKIM tests passing.

Any idea why AOL is putting this block on my list's mails to AOL members from my Linode? Does Linode generally have trouble with AOL? Is it because AOL is seeing my Linode IP address fresh and I have to build up reputation (or maybe the previous person who had this IP address "trashed" it somehow?)
Author:  obs [ Sun Jul 22, 2012 6:13 am ]
Post subject:  Re: Do Linode IP have trouble with AOL? (421 DYN:T1 block)
I've never had a problem with Linode and AOL have you checked if the IP is on any spam lists? (What is the IP?)
Author:  hoopycat [ Sun Jul 22, 2012 7:14 am ]
Post subject:  Re: Do Linode IP have trouble with AOL? (421 DYN:T1 block)
AOL's Postmaster Website has information on how to ask AOL to accept your mail, if it isn't coming from a trusted source yet. They generally only accept large volumes of mail from known-good trusted IP addresses; like most recipients, they don't care about SPF or DKIM until they've decided to accept a message.

The site also has a list of the error code explanations:

Quote:
421 DYN:T1
The IP address you are sending from has been temporarily rate limited due to lack of whitelisting, unexpected changes in volume, or poor IP reputation.


So, most likely, the IP address you're sending from isn't whitelisted, and it suddenly started sending a lot more mail than it used to. The quick and easy way to handle this is to do the migration over the span of a few months; start routing a couple deliveries per day via the new server, then a couple more, etc, until it's all good. But I suppose the horse is already out of the barn on this one. At least it's a 4xx error, so it'll keep retrying until it goes through (or bounces).
Author:  QuantumMechanic [ Sun Jul 22, 2012 8:06 am ]
Post subject:  Re: Do Linode IP have trouble with AOL? (421 DYN:T1 block)
obs wrote:
I've never had a problem with Linode and AOL have you checked if the IP is on any spam lists? (What is the IP?)


I have checked (I used MxToolbox's meta-checker (http://www.mxtoolbox.com/blacklists.aspx)) and
it said it checked my IP (66.175.210.91) against 105 RBLs and it was not on any of them (though eight of the RBLs timed out).
Author:  QuantumMechanic [ Sun Jul 22, 2012 8:10 am ]
Post subject:  Re: Do Linode IP have trouble with AOL? (421 DYN:T1 block)
hoopycat wrote:
AOL's Postmaster Website
The quick and easy way to handle this is to do the migration over the span of a few months; start routing a couple deliveries per day via the new server, then a couple more, etc, until it's all good. But I suppose the horse is already out of the barn on this one. At least it's a 4xx error, so it'll keep retrying until it goes through (or bounces).


That's not really possible -- the server being migrated from goes away next month :)

Also, this isn't a high-volume list. It's only 10-30 messages per day, and there are only 170 addresses on it, of which only 12 are AOLers. So AOL is only getting 120-360 messages/day from my IP address. And the day of the migration there were only about 5 messages.

But thanks for the pointer to that Postmaster website!
Author:  gthornejr [ Mon Jul 23, 2012 3:55 pm ]
Post subject:  Re: Do Linode IP have trouble with AOL? (421 DYN:T1 block)
I had the identical problem last year when moving to Linode. In my case, a user had an email box that forwarded to their AOL address. When the 4xx errors started, none of my users' emails to AOL (or netscape.com) would get delivered. I attempted to contact the Postmaster using the form, which I had successfully done in the past to set up feedback loops. Their form accepted my input but I I never heard back from them. Since this server was a production server, I had to temporarily route all AOL email through my old server until I could complete the move.

I opened up a paid web-only account with AOL and worked my way to level 2 support to get someone to contact the Postmaster department. I was told they are actually located in an office "unreachable by phone", so all correspondence has to be done through that site. After a few weeks of pressing support, I finally got an email back from the postmaster saying our server had been whitelisted.

Hopefully your experience will be speedier and more pleasant!

Gary Thorne
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