Yahoo delays, part 3: Yahoo speaks

Yahoo is aware of the recent problems and have been working feverishly to fix them. A Yahoo employee posted to a mailing list earlier today, explaining some of the recent issues. The summary is:
1) The Yahoo delays are a result of a tighter spam filtering policy. The delays are the result of the system erroneously recognizing email as spam and deferring delivery. They do believe that retrying long enough will result in all mail being delivered to Yahoo recipients.
2) They have been continually making fixes to the system over the last few days and senders should see queues start to empty over the next few hours.
3) They believe the adjustments made will resolve the deferral problems. If you continue to see problems, you can contact them through the form at http://postmaster.yahoo.com/.
4) They are working to provide more self-serve information at http://postmaster.yahoo.com/ as well as timely service updates.
Loose ends from my previous Yahoo posts:

  1. The rumors of an attack were just that, rumors.
  2. The Yahoo blog post about outbound servers is unrelated to the problems seen by senders recently. Outbound SMTP servers are not the same as the MX machines.

Good news all around. Thanks to the people at Yahoo for working so diligently to fix the problems.

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Yahoo delays

You may have noticed increase in delays and rejections from Yahoo. I am certainly seeing a lot of customers complaining and hearing a lot of other delivery people commenting on problems getting mail into Yahoo. I have even heard from multiple ISPs that are struggling with full queues and delayed email.
No solutions or suggestions right now, just that everyone is having problems right now. I expect it will take some time for the backlogs to dissipate, even after the underlying problem is fixed. If I hear anything more I will post it here.

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Yahoo and Spamhaus

Yahoo has updated and modified their postmaster pages. They have also put a lot of work into clarifying their response codes. The changes should help senders identify and troubleshoot problems without relying on individual help from Yahoo.
There is one major change that deserves its own discussion. Yahoo is now using the SBL, XBL and PBL to block connections from listed IP addresses. These are public blocklists run by Spamhaus. Each of them targets a different type of spam source.
The SBL is the blocklist that addresses fixed spam sources. To get listed on the SBL, a sender is sending email to people who have never requested it. Typically, this involves email sent to an address that has not opted in to the email. These addresses, known as spamtraps, are used as sentinel addresses. Any mail sent to them is, by definition, not opt-in. These addresses are never signed up to any email address lists by the person who owns the email address. Spamtraps can get onto a mailing list in a number of different ways, but none of them involve the owner of the address giving the sender permission to email them.
Additionally, the SBL will list spam gangs and spam supporters. Spam supporters include networks that provide services to spammers and do not take prompt action to remove the spammers from their services.
The XBL is a list of IP addresses which appear to be infected with trojans or spamware or can be used by hackers to send spam (open proxies or open relays). This list includes both the CBL and the NJABL open proxy list. The CBL list machines which appear to be infected with spamware or trojans. The CBL works passively, looking only at those machines which actively make connections to CBL detectors. NJABL lists machines that are open proxies and open relays.
The Policy Block List (PBL) is Spamhaus’ newest list. Spamhaus describes this list as

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Yahoo delays, part 2

A number of people have posted to various mailing lists and made blog posts pointing to the Yahoo Mail blog post discussing recent problems Yahoo was having with mail. The general feeling seemed to be “AHA! That’s what is wrong!”
Unlike many of my peers, I do not think this explains the delivery problems senders have been seeing while attempting to deliver mail to Yahoo. The Yahoo mail blog article is talking about the Yahoo outgoing mailservers (smarthosts) for their non-webmail users. It is extremely unlikely that these are the same servers used for incoming email.
While I sympathize with everyone who had the AHA! moment and thought their delivery problems were being acknowledged and addressed by Yahoo! I do not think this is really what that blog post is saying.
I am hearing from people that Yahoo is aware of a problem with delayed incoming email, and they are working on fixing it. This does seem to be a broader problem than just bulk mailers, I am hearing from small and mid-size ISPs that they are having significant problems delivering email to Yahoo, too.
For more information about what Yahoo is doing to filter mail check out my previous post Greylisting: that which Yahoo! does not do.

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