We saw this over noon hour yesterday (Wednesday), and now again today, since
6:19 am U.S. Central:
421 4.2.1 "Service unavailable. Please try again later."
We're seeing this on multiple IPs, such as 188.8.131.52, 184.108.40.206,
220.127.116.11, and 18.104.22.168.
The last email that we delivered was 2:40 am -- though one did deliver at
Downdetector shows that AOL is having some kind of email issue:
mailop mailing list