Exchange 2016 User Mailboxes Migrated to Exchange 2019 | IMAP | SMTP Permission

Copper Contributor

We have migrated from Exchange 2016 to Exchange 2019 Servers.
Exchange 2016 servers have been shutdown now.


When I initially setup a new servers, i created a new user and mailbox for each server.


Problem: When we configure IMAP Profile in Thunderbird client (windows/Linux) the below happens:


1) new users on new servers - works fine

2) old users who were migrated from 2016 - the issue pops up when sending the email. receiving works fine.


The error message is as shown


1 Reply
Does this problem occur for newly created messages? When doing upgrade (Exchange 2016 to 2019), all you need to do is migrate the mailboxes from a DB on Exchange 2016 to a DB on Exchange 2019, and all the configuration is retained. From your description, it sounds like you've created new mailboxes and exported/imported messages to these new mailboxes