Because off an extended power failure, our Exchange 2016 mail server was moved to a backup site.
The server IP was changed (LAN), but nothing else changed. Issues started to appear, such as OWA opens, but we are unable to send / receive mail.
Mail to the send connectors under mail flow settings also stopped working.
We recently migrated Exchange 2013 to Exchange 2016.
Exchange 2013 gave several errors and not starting some services, but we left the server running whilst transferring mailboxes to 2016, etc.
Exchange 2016 is running from a "backup" DC in the backup site.
Upon clicking new e-mail in OWA, the new mail window opens, but clicking "send" - nothing happens.
The e-mail does not go to the Sent Items folder, neither does anything comes into the inbox.
No specific errors in the event log (Exchange 2016)
No configuration changes happened on the 2016 server, except for an IP change for the LAN.
After one upgrades say Exchange 2013 to Exchange 2016, and Exchange 2013 has not yet been uninstalled,
What affect does it have on the mail flow and mail transport?
All mail flow receive and send connectors have been updated to the 2016 server.