How to automatically set calendar publishing range to 12 months (OneYear) for all new mailboxes in Exchange Online?

Question

How to automatically set calendar publishing range to 12 months (OneYear) for all new mailboxes in Exchange Online?

Noa Saverio De Paola 20

Hi everyone,

By default, published/shared calendars in Exchange Online only show the next 6 months of events. I know I can extend a single mailbox to 12 months using PowerShell:

Set-MailboxCalendarFolder -Identity "******@domain.com:\Calendar" -PublishEnabled $true -PublishDateRangeFrom SixMonths -PublishDateRangeTo OneYear

This is also described in this thread: https://learn.microsoft.com/en-gb/answers/questions/1531591/how-to-view-published-shared-calendar-more-than-6

My question: Is there any way to make this the DEFAULT for newly created mailboxes, so that the publishing range is automatically set to OneYear (12 months) for every new user, without having to run the command manually for each mailbox?

Context: Every year we onboard a group of new users, and we would like their calendars to be visible for 12 months to an external partner tenant (cross-tenant sharing) right from the start, instead of having to remember to run the PowerShell command for each new person.

What I have found so far:

There does not seem to be a tenant-wide default setting for PublishDateRangeTo in the Exchange Admin Center or the Microsoft 365 Admin Center.
The only options seem to be: (a) run a script periodically against all mailboxes, or (b) include the command in a provisioning/onboarding script.

Is there an officially supported way to enforce a 12-month publishing range as a default for all new mailboxes? Or is a scheduled script / provisioning script the only supported approach?

Thanks in advance for any guidance!

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Answer 1

Michelle Nguyen 1,180 Independent Advisor

Hi @Noa Saverio De Paola

Your understanding is correct. Exchange Online does not currently provide a tenant-wide mailbox policy or organization-level setting that changes PublishDateRangeTo to OneYear automatically for every newly created mailbox.

PublishDateRangeTo is a property of the individual mailbox calendar folder and is configured through Set-MailboxCalendarFolder. The cmdlet documentation does not provide a switch or policy object for setting this value as a default for future mailboxes.

Add Set-MailboxCalendarFolder to your mailbox provisioning or onboarding process.
Run a scheduled PowerShell automation that detects newly created mailboxes and applies the required configuration.
Optionally, run a periodic compliance script against all applicable mailboxes to correct any mailbox that does not have the desired value.

For example:

Connect-ExchangeOnline
Get-EXOMailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited |
 ForEach-Object {
 $calendarIdentity = "$($_.PrimarySmtpAddress):\Calendar"
 try {
 Set-MailboxCalendarFolder `
 -Identity $calendarIdentity `
 -PublishEnabled $true `
 -PublishDateRangeFrom SixMonths `
 -PublishDateRangeTo OneYear `
 -ErrorAction Stop
 Write-Host "Updated: $($_.PrimarySmtpAddress)"
 }
 catch {
 Write-Warning "Could not update $($_.PrimarySmtpAddress): $($_.Exception.Message)"
 }
 }

For production automation, it would be better to detect the default calendar folder instead of assuming that its name is always Calendar, because the folder name can be localized according to the mailbox language.

One additional point is that Set-MailboxCalendarFolder controls calendar publishing, such as published calendar URLs. It is not the same as tenant-to-tenant free/busy sharing. Microsoft documents this cmdlet specifically as configuring calendar publishing or sharing settings on an individual mailbox calendar folder.

If the external partner accesses the calendars through an Organization Relationship, sharing policy, or another cross-tenant free/busy configuration, PublishDateRangeTo might not control what they can see. It would therefore be worth confirming whether your implementation uses:

Published HTML or ICS calendar URLs, or
Exchange organization relationships and free/busy sharing.

Ref: Set-MailboxCalendarFolder

I hope this helps.

Noa Saverio De Paola 20 Reputation points

2026-08-25T06:44:44.19+00:00

Hi @Michelle Nguyen

Thank you so much, this really helped and brought a lot of clarity!

You confirmed what I suspected: there is no tenant-wide default for PublishDateRangeTo, so a provisioning step or a scheduled PowerShell automation is the way to go.

Thanks also for pointing out that Set-MailboxCalendarFolder controls calendar publishing and is not the same as cross-tenant free/busy sharing. I will double-check which mechanism our partner actually uses. The tip about not hardcoding the localized "Calendar" folder name is much appreciated too.

Thanks again for your great answer!
Michelle Nguyen 1,180 Reputation points Independent Advisor

2026-08-26T14:24:07.11+00:00

Hi @Noa Saverio De Paola

Thank you for the update. Please let me know if you need any further information.
Noa Saverio De Paola 20 Reputation points

2026-09-03T06:52:48.36+00:00

Hi again @Michelle Nguyen

You were right that PublishDateRangeTo is not the correct setting for us. I tested it and it had no effect.

In our case the calendar is shared via an Exchange sharing invitation, not a published URL (ExtendedFolderFlags shows SharedViaExchange). The external user in the partner tenant has Reviewer permissions and does see full appointment details, so the detail level is fine. But they only see exactly 6 months into the future, appointments beyond that are not visible.

Is there any supported way to extend this 6-month window for Exchange-based cross-tenant shared calendars, or is this a hard product limit? And would creating an organization relationship change the visible time range at all, or does it only affect free/busy in the scheduling assistant?

Thanks a lot!

Best regards,
Noa
Michelle Nguyen 1,180 Reputation points Independent Advisor

2026-09-04T08:37:21.0366667+00:00

Hi @Noa Saverio De Paola

Thank you for the additional testing. Since the calendar shows SharedViaExchange, PublishDateRangeTo is not applicable. That parameter controls calendar publishing through HTML or ICS URLs, not calendars shared through Exchange invitations.

A sharing policy can allow full calendar details through CalendarSharingFreeBusyReviewer, but Microsoft does not document a property in the sharing policy that controls how many future months are synchronized or displayed.

Creating an organization relationship would not modify the range of the existing Reviewer calendar. Organization relationships are used for organization-level free/busy and MailTips scenarios, rather than granting or modifying Reviewer access to an individual Calendar folder.

Based on the currently documented Exchange Online controls, there is no supported administrator setting to extend the six-month future window you are seeing for this type of cross-tenant shared calendar. However, Microsoft’s documentation does not explicitly describe the six-month window as an immutable product limit, so I recommend reporting the behavior through a Microsoft 365 support request for authoritative confirmation.

Also note that Microsoft is introducing Microsoft 365 Cross-Tenant Access Policy to replace EWS-based cross-tenant calendar-sharing configurations. You should review the relevant Message Center notice before changing the existing configuration, although the migration documentation does not say that it extends the calendar’s visible date range.
Noa Saverio De Paola 20 Reputation points

2026-09-08T06:02:08.81+00:00

Hi @Michelle Nguyen

Thanks a lot. That confirms what we suspected.

In the meantime we found that the publishing range was not actually the root cause in our case. Our partner tenant's default sharing policy only allowed CalendarSharingFreeBusySimple towards external domains, so every share was downgraded to the published free/busy feed, which stops after 6 months. We created a dedicated sharing policy for our domain with CalendarSharingFreeBusyDetail, assigned it to the mailbox, and had the user remove and re-create the share with "Can view all details". The calendar now syncs the full 12 months.

For the onboarding part we will follow your suggestion and handle it via a provisioning script. Marking your answer as accepted, thanks again!