We run one Exchange 2016 server on Windows 2012 R2. In Mid May we found one user mailbox "user1" was corrupted. So we backed up all his emails, deleted the mailbox, and recreated a new one. The user also had one alias called "alias1",
and it has been added to the account as well.
Then after about a month, I found all internal emails are working fine, but incoming emails are working only with user1@mydomain.com, only 1 or 2 of every 10 incoming emails to alias1@mydomain.com are received, all the other emails received by Exchange
are just queued somewhere unknown. For example I queried two emails from the same sender to alias1@mydomain.com below.
The one still queued somewhere after nearly a month:
6/18/2019 9:30 AM exchange.mydomain.local
Message was received by exchange.mydomain.local from myincominggateway.com.
7/11/2019 9:59 AM exchange.mydomain.local
Message delivery is taking longer than expected. There may be system delays. For more information, contact your email admin.
The one received 3 hours later on the same day was however delivered immediately:
6/18/2019 12:05 PM exchange.mydomain.local
Message was received by exchange.mydomain.local from myincominggateway.com.
6/18/2019 12:05 PM exchange.mydomain.local
The e-mail address for recipient "alias1@mydomain.com" was updated to the e-mail address "user1@mydomain.com". The message is in the process of being delivered.
6/18/2019 12:05 PM exchange.mydomain.local
The message has been transferred from exchange.mydomain.local to EXCHANGE.Mydomain.local.
Delivered
6/18/2019 12:05 PM exchange.mydomain.local
The message was successfully delivered.
Incoming messages are queued forever
