This month I had 2 customers how had some weird settings in outlook.
They both received undeliverable email, stated the receiving mailbox was full. They both didn’t send any email to this mailbox. With some testing, I quickly saw the reason: all sending mail was forwarded to this email address, and this mailbox was full.
Quickly I checked the rules of this outlook, and there was no forwarding rule.
After this I checked the OWA ruleset, and there was also no forwarding rule.
Off course the solution had to be powershell 😊
Powershell check :
How to check if a forward rule exists for all users :
(a rule can exist on both ForwardingAddress and ForwardingSmtpAddress)
Get-Mailbox | select UserPrincipalName, ForwardingAddress, DeliverToMailboxAndForward Get-Mailbox | select UserPrincipalName, ForwardingSmtpAddress, DeliverToMailboxAndForward You can also check for forwarding rule on one mailbox : Get-Mailbox <identity> | select UserPrincipalName, ForwardingAddress, DeliverToMailboxAndForward Get-Mailbox <identity> | select UserPrincipalName, ForwardingSmtpAddress, DeliverToMailboxAndForward
The users mailbox has a forward to the Gmail mailbox, and DeliverToMailboxAndForward is set to True
Solution :
After finding a forwarding rule you can delete this rule in Powershell by forwarding the mailbox to ‘nothing’, and off course disable the forwarding.
Change the forward :
You can change the forward to ‘nothing’ by forwarding it to ‘$Null’
Set-Mailbox <MailBox> -ForwardingAddress $Null Set-Mailbox <MailBox> -ForwardingSmtpAddress $Null
Check the mailbox again:
Get-Mailbox <MailBox> | select ForwardingSMTPAddress,DeliverToMailboxandForward
The forwarding (Gmail) email address is now removed from the rule
You can now disable the forward :
Set-Mailbox <MailBox> -DeliverToMailboxAndForward $False
Execute the command
Check the mailbox again:
Get-Mailbox <MailBox> | select ForwardingSMTPAddress,DeliverToMailboxandForward
The option DeliverToMailboxAndForward is now set to false, and no forward is active anymore.
