Increase in bounces at Y!

I’ve been seeing reports over the last few days about an increase in bounces at Yahoo. Reliable people are telling me they’re seeing some increase in “invalid user” bounces.
You may remember Yahoo announced an overhaul of their mail product back in December. Reliable sources tell me that this is more than just interface revamp. In the back end, Yahoo! is removing older products with few users and security problems. This fits in with the changes CEO Mayer has been making with the company: slim down and stop supporting unprofitable products.
It makes sense that while engineers are looking at the guts of the email program and cleaning up the cruft, they will also disable long unused email addresses. This will result in higher unknown users for some senders.
What’s interesting to me is that the reports are somewhat sporadic. Some senders are seeing a huge percentage of bounces, some are seeing the normal percentage. I expect this difference isn’t anything more than how actively a sender purges based on engagement. Senders that purge unengaged addresses are going to have already removed a lot of the addresses Yahoo! is now purging from their database. Senders that keep sending to their whole list, are going to see a lot of unknown user bounces.
I’ve asked a few folks and people who’ve responded told me that spot checks showed all the addresses turning up as invalid had no engagement for long periods of time.
If you are seeing a lot of bounces at Yahoo! over the last few days, you need to remove those addresses from your lists. I also recommend looking at the engagement statistics of these newly purged recipients. This will tell you, approximately, what an abandoned address profile looks like. You can use that information to make good decisions about purging unengaged users at other ISPs as well. Not only does this lower costs, because you’ll be sending to less non-responsive email addresses, it will also improve delivery at many ISPs.