Background - Noah Wilde was having an issue in Oct. 2023 where his out of office / autoreply kept re-enabling itself.   I (Blair) reached out to Excaltech for assistance with troubleshooting and they suggesting trying to alter the settings using Powershell/Command Line commands.  That brought to the surface an issue with even running the necessary command line commands and Excaltech assisted with resolving that as well.  So, this KB article touches on both.

• The commands are (and were attempted to be) run on EX4 via Remote Desktop.  On that server, open a Windows Powershell session (as Administrator; though not sure if that's a deal-breaker or not)  Note - it's Windows Powershell, NOT Exchange Management Shell.
• The command to modify the autoreply setting is set-mailboxautoreplyconfiguration.  The syntax for this is documented here - https://learn.microsoft.com/en-us/powershell/module/exchange/set-mailboxautoreplyconfiguration?view=exchange-ps
• The Excaltech ticket associated with this incident is ticket #171348
• The TS Ticket associated with this incident is #35264
• Once Excaltech resolved the issue with being able to run this command, it seems to have helped with resolving the autoreply settings and the command did successfully allow me to alter the configuration.

UPDATE - Noah ultimately discovered and admitted that he was utilizing some sort of "Flow" functionality in Outlook that apparently added replies as some sort of conditional / scheduled workflow.  He has now removed those.  I also, for good measure, disabled Cached Exchange Mode on his local Outlook installation just in case it was rewriting or overriding settings made via either the web O365 or command line.

BB - 10/13/23