AOL transmitting 4xx error for user unknown

AOL is currently returning “451 4.3.0 <invaliduser@aol.com>: Temporary lookup failure” in some cases when they really mean “550 user unknown.” This message from AOL should be treated as 5xx failure and the message should not be retried (if at all possible) and the failure should be counted as a hard bounce for list management purposes.
This is something broken at AOL’s end, and the guys with the magic fingers that keep the system running are working to fix it. Right now there doesn’t seem to be an ETA on a fix, though.
Even if you are a sender who is able to stop the retries, you may see some congestion and delays when sending to AOL for the time being. Senders who don’t get the message, or who are unable to stop their MTAs from retrying 4xx mail will continue to attempt delivery of these messages until their servers time out. This may cause congestion for everyone and a noticeable  slowdown on the AOL MTAs.
AOL blog post on the issue
HT: Annalivia

Tagged.com and the courts
Social network spam

Related Posts

AOL announces new postmaster pages

The new AOL postmaster pages are live at http://postmaster.info.aol.com/

Read More

Soft bounces and rate limiting

What is your policy for handling soft bounces? What do you consider a soft bounce? What is the right thing to do about soft bounces?
The first step in talking about soft bounces is to define them. When I talk about soft bounces, I mean mail that has been rejected with a 4xx response during the SMTP transaction. As described by RFC5321, when a recipient MTA responds with a 4xx it is telling the sending MTA “Wait! I can’t take this mail right now. Come back a little later and try again.” The sending MTA will then continue to attempt to deliver the message until either it is delivered or until it hits the max delivery time, usually 3 – 5 days.
In a well behaved and RFC compliant MTA, messages that have reached the maximum time without delivery due to 4xx rejections will be converted to permanent rejections (5xx). With a correct MTA, this means too many emails in a row timing out shoud result in an email address being removed from future mailings.
For a number of reasons some ISPs, notably Yahoo, are using 4xx responses to slow down mail from some senders. Many senders treat this as a inconvenience and a frustration and try to figure out how to get around the rate limiting. The UK DMA published an article on soft bounces with the following words of wisdom.

Read More

AOL layoffs and postmaster changes

As most of you probably know, AOL went through a serious round of layoffs yesterday. Unlike previous layoffs this one did hit the postmaster team pretty hard. Anna posted this morning that she was the only non-programming member of the postmaster team left in the US. This means there are a number of experienced folks looking for work with experience managing delivery for a large outfit. More info is on her blog.
While I don’t have any firm data, I expect that this is going to significantly affect the support that senders see from AOL. I know many of us have held up AOL as the poster child for how ISPs should interact with senders. That era is drawing to a close.
These layoffs come as AOL has migrated to a new mail system and a lot of senders are seeing new and different error messages. I do believe the folks handling the mail system and the migration are still there and are feverishly working to resolve problems caused by the migration. Right now things are in flux and senders should probably expect delays in getting support from AOL for delivery problems.
UPDATE: Matt Vernhout has a list of suggestions for how to deal with AOL delivery issues.

Read More