1.  Enable this in powershell first

#Enable Exchange cmdlets

add-pssnapin *exchange* -erroraction SilentlyContinue

2. THEN use one of the following:

 

Forward mails to another mailbox:

Set-Mailbox [email protected] -ForwardingAddress [email protected]

Forward mailbox without saving a local copy:

Set-Mailbox [email protected] -ForwardingAddress [email protected] -DeliverToMailboxAndForward $false

Forwarding mails to another external mailbox:

Set-Mailbox [email protected] -ForwardingSmtpAddress [email protected]

Forwarding mails to another external mailbox without saving a local copy:

Set-Mailbox [email protected] -ForwardingSmtpAddress [email protected] -DeliverToMailboxAndForward $false

Apply the forwarding to users in mass:

Get-Mailbox | Where {$_.RecipientType -eq “UserMailbox”} | Set-Mailbox -ForwardingAddress [email protected]

Apply the forwarding to users to be sent to external users in mass:

Get-Mailbox | Where {$_.RecipientType -eq “UserMailbox”} | Set-Mailbox -ForwardingSmtpAddress [email protected]

Get forwarding Info of a user:

Get-Mailbox -Identity [email protected] | fl DeliverToMailboxAndForward, ForwardingAddress, ForwardingSmtpAddress

Remove mail forwarding:

Set-Mailbox [email protected] -ForwardingAddress $null

Remove mail forwarding sent to an external user:

Set-Mailbox [email protected] -ForwardingSmtpAddress $null

Remove mail forwarding to users in mass:

Get-Mailbox | Where {$_.RecipientType -eq “UserMailbox”} | Set-Mailbox -ForwardingAddress $null

Remove mail forwarding sent to external users to users in mass:

Get-Mailbox | Where {$_.RecipientType -eq “UserMailbox”} | Set-Mailbox -ForwardingSmtpAddress $null