Convert resource mailbox to a user mailbox

Based on my audit for a client I found that a user mailbox was at sometime converted to a resource mailbox. There is no convert button/ link to switch it back. I still don’t know how, or why this would have happened.

Anyways, for someone who may come across this weird issue, here is the fix for it.

This will convert it from a shared mailbox, or a resource mailbox to a user mailbox.

Extending the Booking days for Conference Room Calendar (Resource)

By default Office365 limits Resource booking days to just 180 days. The maximum days it can be booked for 1080 days.

I like to make resource booking days 1 year from the day of making the reservation/ appointment. Now instead of visiting each calendar and making the change, powershell can help us out.

Happy Booking!

Assign a Room Mailbox Permissions

If we want to check the detail information of the room mailbox schedule or change the permission level of the Calendar permission.  We should do the following steps:

  •  Add a user as a full permission to the room mailbox via PowerShell:

    Assign Permission Add-MailboxPermission -Identity “[email protected]” -User “[email protected]” -AccessRights Fullaccess -InheritanceType All

  • Open room mailbox with OWA
  • Login to user who have the full permission of room mailbox by using OWA.
  • Click on “your alias” at top right corner and select room mailbox
  • When the OWA open room mailbox, we can click on “calendar” -> Share -> “Share this calendar”  and select the share permission. Then, we can select the person and send the announcement email.

On the Client Side the user will be able to the see the only if they have permissions. If no permissions are assigned it will give a warning saying it is unable to connect. This will go away once the permissions are set right!

  1. Open OWA (Outlook Web apps) by opening
  2. Calendar – > My Calendars  -> open “other Calendars” ,then input the alias of the Room-mailbox

Microsoft Article: Create A New Room Mailbox