We’ve known for a while that AOL email infrastructure is going to be merging with Yahoo’s, but apparently it’s happening sooner than anyone expected.
The MXes for aol.com will be migrated to Yahoo infrastructure around February 1st. Reading between the lines I expect that this isn’t a flag day, and much of the rest of the AOL email infrastructure will be in use for a while yet, but primary delivery decisions will be made on Yahoo infrastructure.
The AOL and Yahoo postmaster teams are pretty smart so I assume they’ll have made sure that their reputation data is consistent, and be doing everything else they can do to make the migration as painless as possible. But it’s a major change affecting a lot of email, and I wouldn’t be surprised to see some bumpiness.
If you’ve done anything … unwise … with delivery to AOL addresses, such as hard-wiring MXes for delivery to aol.com, you should probably look at undoing that in the next week or so. I’m guessing the changeover will happen at the DNS level, so if you’ve nailed down delivery IPs for aol.com you might end up trying – and probably failing – to deliver to the old AOL infrastructure.