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Maximizing Deliverability
Spencer Kollas Director of Deliverability Services
February 28, 2008
Yahoo Deferrals
Over the last week there has been a lot of news around some clients have seen an increase in the 4xx errors coming from Yahoo!. There have been reports that Yahoo! was under some type of attack from various spamming organizations and that they were using this method to fight off those attacks. Others believed that Yahoo! had officially put in a grey-listing methodology as part of their anti-spam efforts. Neither of these beliefs are correct.
Yahoo! has verified that they have recently put in new, more aggressive measures to fight illegitimate mail coming into their servers. While they have acknowledged that this may be have some affect legitimate mailers they are working on fine-tuning these systems. Their goal as always is to make sure that the legitimate mail that people want to receive gets to their end users, and that which they don’t is blocked. According to Yahoo!, any legitimate mail that has been received but not yet have been delivered will eventually reach the intended recipient as their inbound mail queues drain. They have asked for everyone’s understanding during this time and hope to have the issue resolved soon.
If you're seeing 451 4.70 [TS01] or [TS02] errors you should wait at least 4 hours before trying to redeliver the mail.
As always if you have any questions please feel free to reach out to our support group or for this particular issue you can go to http://postmaster.yahoo.com.
Posted by: Spencer Kollas at 1:49 PM
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My understanding is that Strongmail offers "live updates" to subvert such issues automatically? At least, this seems to be the story from the sales team there.
Comment by Todd Marin – February 29, 2008 9:35 AM
While you are correct Live Updates does help with subverting these types of issues, the program is based information we gather from the ISPs about their throttle limits, bounce categorizations etc. While we try to stay as much ahead of the game as possible there are times such as this that ISPs will change the way that they filter mail once it is received into their system and those types of issues can not be subverted.
Hope this clears it up a bit.
Comment by Spencer Kollas – February 29, 2008 9:47 AM
Yes, but this was the story before the ISP relations team was built there so it's hard to understand how the program could've been based on resources that didn't exist.
Comment by Todd Marin – February 29, 2008 11:00 AM
We at StrongMail have always had an ISP relations team, but these items are also determined by looking at the DSNs and other metrics.
Comment by Spencer Kollas – February 29, 2008 11:12 AM