Configure an autoreply (OOO) message for Microsoft 365 Groups

Microsoft 365 Groups have long been positioned as the better version of a distribution list, and there is some merit to this. Although as much as Microsoft’s marketing team would want us to just forget about the good old DL/DG, in some cases they remain a viable, lightweight (as in no extra baggage added in terms of a SharePoint site or other artifacts), and cheaper alternative (dynamic DGs cost nothing, Microsoft 365 Groups with dynamic membership require Azure AD Premium).

In theory, the combination of a distribution list and a shared mailbox, to which we can approximate a Microsoft 365 Group to, should offer best of both worlds. In practice, Microsoft long neglected this part of the Group experience. Things seems to have changed recently, with the introduction of features such as Moderation. Most recently, Microsoft added a feature that sits on the other side of the spectrum, as in it is technically part of the “mailbox” experience. Namely, we can now configure automatic replies, also known as OOO, for a Microsoft 365 Group. Here’s how.

The bad news is, none of the UI bits currently expose this, so you will have to use PowerShell. The good news is that you can use the good old Set-MailboxAutoReplyConfiguration cmdlet and the same set of parameters as available for regular mailboxes. You don’t even need to specify the –GroupMailbox switch, which is required by some of the “mailbox” cmdlets when used against a Microsoft 365 Group. So, to check the current autoreply configuration for a given Group, run the Get-MailboxAutoReplyConfiguration cmdlet:

Get-MailboxAutoReplyConfiguration TeamSite_12c96e98-45fd-4591-93e5-cca4fd91666b

RunspaceId : cb1e9511-0fea-4259-9fde-8f5e010ce0b5
AutoDeclineFutureRequestsWhenOOF : False
AutoReplyState : Disabled
CreateOOFEvent : False
DeclineAllEventsForScheduledOOF : False
DeclineEventsForScheduledOOF : False
EventsToDeleteIDs :
EndTime : 10/06/2022 08:00:00
ExternalAudience : All
ExternalMessage :
InternalMessage :
DeclineMeetingMessage :
OOFEventSubject :
StartTime : 09/06/2022 08:00:00
Recipients :
ReminderMinutesBeforeStart : 0
ReminderMessage :
MailboxOwnerId : TeamSite_12c96e98-45fd-4591-93e5-cca4fd91666b
Identity : TeamSite_12c96e98-45fd-4591-93e5-cca4fd91666b
IsValid : True
ObjectState : Unchanged

As expected, no autoreply is configured, which is the default state. To configure the OOO reply, we can now use the Set-MailboxAutoReplyConfiguration cmdlet, with the set of parameters as follows:

  • AutoReplyStateEnabled to toggle autoreplies ON, Disabled to toggle it OFF, Scheduled to specify a start and end time between which to send OOO replies.
  • InternalMessage – the message that will be sent to internal recipients (as in users within your own tenant).
  • ExternalMessage – the message that will be sent to external recipients (as in users outside of your tenant). Remember that by default, Microsoft 365 Groups restrict external delivery, so configuring an external message only makes sense when you’ve toggled the RequireSenderAuthenticationEnabled flag.
  • ExternalAudience – optionally limit the set of external recipients to reply to. Valid values are None, Known (as in entries present in the mailbox’s Contacts folder) and All. However, as Microsoft 365 Groups still do not expose the Contacts experience, the Known value will not have the desired effect.
  • EndTime and StartTime – used when AutoReplyState is set to Scheduled.

For example, this cmdlet will enable OOO replies for the specified Microsoft 365 Group, with a simple message:

Set-MailboxAutoReplyConfiguration -Identity TeamSite_12c96e98-45fd-4591-93e5-cca4fd91666b -InternalMessage "This is an OOO reply for Microsoft 365 Group" -ExternalMessage "Not enabled" -AutoReplyState Enabled

As you’d expect, the internal and external message you specify is saved in HTML format, as evident from the Get-MailboxAutoReplyConfiguration output:

Get-MailboxAutoReplyConfiguration TeamSite_12c96e98-45fd-4591-93e5-cca4fd91666b

RunspaceId : cb1e9511-0fea-4259-9fde-8f5e010ce0b5
AutoDeclineFutureRequestsWhenOOF : False
AutoReplyState : Enabled
CreateOOFEvent : False
DeclineAllEventsForScheduledOOF : False
DeclineEventsForScheduledOOF : False
EventsToDeleteIDs :
EndTime : 10/06/2022 08:00:00
ExternalAudience : All
ExternalMessage : <html>
<body>
Not enabled
</html>

InternalMessage : <html>
<body>
This is an OOO reply for Microsoft 365 Group
</body>
</html>

DeclineMeetingMessage :
OOFEventSubject :
StartTime : 09/06/2022 08:00:00
Recipients :
ReminderMinutesBeforeStart : 0
ReminderMessage :
MailboxOwnerId : TeamSite_12c96e98-45fd-4591-93e5-cca4fd91666b
Identity : TeamSite_12c96e98-45fd-4591-93e5-cca4fd91666b
IsValid : True
ObjectState : Unchanged

At this point, you can send a test message to the Group and observe the result:

Interestingly, no MailTip is presented when an OOO message is configured for a Microsoft 365 Group, in contrast with the mailbox experience. But hey, you cannot have it all!

Now, there are a bunch of additional parameters you can use with the Set-MailboxAutoReplyConfiguration, which control the availability info and meeting responses for the mailbox over the period for which OOO is scheduled. For example, you can use the –CreateOOFEvent switch together with the –OOFEventSubject parameter to “block” the time scheduled as OOO within the Group’s calendar. However, those parameters do not seem to work as expected (or at all) with Microsoft 365 Groups, at least in my experience. In any case, you can get additional information on them via the official documentation. Do let me know if you manage to get them working!

This entry was posted in Azure AD, Exchange Online, Microsoft 365, Office 365, PowerShell. Bookmark the permalink.

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