I maintain a mail server. Recently messages sent to valid recipients on gmail, yahoo, and now roadrunner email addresses are bounced with similar messages: Here's one from gmail:
The message, sent by
[email protected], can not be delivered to following recipient(s):
*recipient*@gmail.com
There was a fatal SMTP error.
Fatal DNS error: exchanger alt4.gmail-smtp-in.l.google.com. does not exist
Delivery History Follows:
[DLVR 000020 19-12-12 14:21:21] Delivering item 5573
[DLVR 000020 19-12-12 14:21:21] Resolving MX records for domain gmail.com
[DLVR 000020 19-12-12 14:21:21] Retrieved 5 MX records for domain gmail.com
[DLVR 000020 19-12-12 14:21:21] Delivering mail to 1 recipient(s) at domain gmail.com using exchanger gmail-smtp-in.l.google.com.
[DLVR 000020 19-12-12 14:21:33] Host gmail-smtp-in.l.google.com. does not appear to exist...
[DLVR 000020 19-12-12 14:21:33] Will try next exchanger
[DLVR 000020 19-12-12 14:21:33] Delivering mail to 1 recipient(s) at domain gmail.com using exchanger alt1.gmail-smtp-in.l.google.com.
[DLVR 000020 19-12-12 14:21:45] Host alt1.gmail-smtp-in.l.google.com. does not appear to exist...
[DLVR 000020 19-12-12 14:21:45] Will try next exchanger
[DLVR 000020 19-12-12 14:21:45] Delivering mail to 1 recipient(s) at domain gmail.com using exchanger alt2.gmail-smtp-in.l.google.com.
[DLVR 000020 19-12-12 14:21:57] Host alt2.gmail-smtp-in.l.google.com. does not appear to exist...
[DLVR 000020 19-12-12 14:21:57] Will try next exchanger
[DLVR 000020 19-12-12 14:21:57] Delivering mail to 1 recipient(s) at domain gmail.com using exchanger alt3.gmail-smtp-in.l.google.com.
[DLVR 000020 19-12-12 14:22:09] Host alt3.gmail-smtp-in.l.google.com. does not appear to exist...
[DLVR 000020 19-12-12 14:22:09] Will try next exchanger
[DLVR 000020 19-12-12 14:22:09] Delivering mail to 1 recipient(s) at domain gmail.com using exchanger alt4.gmail-smtp-in.l.google.com.
[DLVR 000020 19-12-12 14:22:21] Host alt4.gmail-smtp-in.l.google.com. does not appear to exist...
[DLVR 000020 19-12-12 14:22:21] Fatal error - host alt4.gmail-smtp-in.l.google.com. does not exist. Will bounce...
[DLVR 000020 19-12-12 14:22:21] Bouncing to sender using bounce address
[email protected]...
Sometimes these emails get through, other times not. I'm at a loss to explain it.