Within the Microsoft 365 Exchange environment, when a user creates a booking calendar, the system automatically creates an unlicensed resource mailbox with an automatically generated username (normally user’s firstname+lastname). Emails sent to this resource mailbox are automatically forwarded to the user’s main mailbox.
We recently had an issue with a customer in Oxford where such bookings resource mailbox was forwarding emails to a completely unrelated user (without saving to the booking’s mailbox). Not sure why this was happening, probably had something to do with how the bookings calendar was created originally.
I couldn’t find a way to access the bookings mailbox in the Exchange admin web portal so had to resort to PowerShell.
Booking’s mailbox forwarding settings can checked like for any other mailbox:
Get-Mailbox | select UserPrincipalName,ForwardingSmtpAddress,DeliverToMailboxAndForward
This indeed showed that the emails were being forwarded to the unrelated user in question.
To fix this, all I had to to was to run the following command:
Set-Mailbox -Identity “” -DeliverToMailboxAndForward $false -ForwardingSMTPAddress “”
August 2024
Oxford, Oxfordshire
