Over the past week or so, we’ve seen a serious issue with hard bouncing addresses from AOL and Cox. These are aliases that ostensibly reached inboxes a week prior, too, according to the 'delivered' metric. Anything on anyone's radar? Investigating to the extent I can.
Haven't heard much. You could check list counts and ask Kiersti Esparza if they know of anything.
If your sends are large to those ESPs, you may need to throttle somehow.
There's been nothing about any specific outages in the email groups I'm a part of (not Marketo-specific.)
That said, if you're noticing certain ESPs are consistently bouncing, have you checked the messages returning with those bounces? That will probably give you a little more insight. I have a couple of hints at what might be happening with AOL, but I haven't dealt with high-volume B2C in a while, so Cox is a little less clear.
Feel free to drop me a line at email@example.com if you'd like to dig a little deeper. Thanks!
Thanks, Josh and Courtney. Will try Kiersti.
The AOL error is some variation of:
554 mtaig-maa01.mx.aol.com ESMTP not accepting connections 421 4.7.0 mtaig-maa01.mx.aol.com Error: too many errors
Unfortunately, the "Error: Too Many Errors" message is essentially saying whatever AOL initially sent back continues to apply. You'll need to dig the root cause from the earliest @aol emails sent when this started occurring.