Microsoft has released security updates for vulnerabilities found in:
Exchange Server 2013
Exchange Server 2016
Exchange Server 2019
These updates are available for the following specific...
Updated Jan 12, 2022
Version 17.0
Blog Post
After applying KB5007409 to our mail servers currently on Exchange 2016 CU 22, our Mitel NuPoint voicemail system is no longer able to connect using IMAP SSL on 993. This literally stopped working as soon as we manually applied the patch to the particular server that is used for this VM to email integration (the patch was run from an elevated command prompt as required). We can still successfully connect using Test-Imapconnectivity using the same AD credentials the VM server uses. The account has delegated access to our mailboxes in order to deliver voicemails to an Inbox. This particular server is not Internet facing.
Update....
Upon further review the AD account that the VM server is using is getting locked out from bad password attempts, nothing has changed in the configuration and the password has been reset and updated in the appropriate places and still cannot connect due to failed login.