New Work hours and location breaks Set-MailboxCalendarConfiguration

Hi All,

I’ve stumbled over this Issue last Week and decided to write a Blog Article about it - so everybody is aware.

In Exchange Online you can use the Get-/Set-MailboxCalendarConfiguration to get or set the Workhours for a Mailbox.

Get-MailboxCalendarConfiguration -Identity a.bohren@icewolf.ch

These are the Settings in Outlook for the Web / New Outlook and even Outlook Classic > Note the + at the end of the Line

What you can do now, is to create office hours for the morning and the afternoon like in the Screenshot below

I’ve captured that with the Browser Tools in the Networking Tab

What happens to the Get-MailboxCalendarConfiguration? It still shows WorkingHoursStartTime and WorkingHoursEndTime - ignoring that Friday is only set to 16:00 😉

Get-MailboxCalendarConfiguration -Identity a.bohren@icewolf.ch

What happens if we set all the End Times to 16:00

Now that’s reflected in Get-MailboxCalendarConfiguration

Get-MailboxCalendarConfiguration -Identity a.bohren@icewolf.ch

The funny thing is, the Lunch break in the Office Hours start exactly on 07.04.2026 - the date i’ve added those Lunch Breaks

What happens if i now set the Working Hours from 07:00 to 15:00 with Set-MailboxCalendarConfiguration

Set-MailboxCalendarConfiguration -Identity a.bohren@icewolf.ch -WorkDays Weekdays -WorkingHoursStartTime 07:00:00 -WorkingHoursEndTime 15:00:00 -WorkingHoursTimeZone "W. Europe Standard Time"

Answer: Nothing happens - still the same

What if we delete the Lunch break

And try to set the Office Hours with Set-MailboxCalendarConfiguration

Set-MailboxCalendarConfiguration -Identity a.bohren@icewolf.ch -WorkDays Weekdays -WorkingHoursStartTime 07:00:00 -WorkingHoursEndTime 15:00:00 -WorkingHoursTimeZone "W. Europe Standard Time"

Nope - that changes nothing

Summary

As soon someone adds multiple Office hours a day - for example lunch break. The Set-MailboxCalendarConfiguration becomes worthless for WorkingHoursStartTime and WorkingHoursEndTime. Even deleting that does not fix it

Regards
Andres Bohren