List all mailboxes that forward to a specific user

Question

I have this script that lists all mailboxes that are forwarding email, however, I am curious if there would be a way to make it return all mailboxes that forward to a specific user. Basically I'm trying to find out every mailbox that forwards mail to "johndoe". Any help would be greatly appreciated! This is for exchange 2007 btw...

Here's the script so far:

$fwds = get-mailbox | Where-Object { $_.ForwardingAddress -ne $null } | select Name, ForwardingAddress

foreach ($fwd in $fwds) {$fwd | add-member -membertype noteproperty -name “ContactAddress” -value (get-contact $fwd.ForwardingAddress).WindowsEmailAddress}

$fwds

Answer 1

Exchange uses CanonicalName for the forwarding address, so you'll need to look that up from the user name. Since it could be a Mailbox, DL, or Contact, the easiest way I know of is to use Get-Recipient, and grab the Identity property.

$RecipientCN = (get-recipient johndoe).Identity
get-mailbox | Where-Object { $_.ForwardingAddress -eq $RecipientCN }

Answer 2

@mjolinor's version works, but is rather slow, since it loads all the mailboxes. On my system it took about 30 seconds to go through ~300 mailboxes.

This can be speed up by adding a filter to the Get-Mailbox command to only return ones that are actually being forwarded, like so:

$RecipientCN = (get-recipient johndoe).Identity
Get-Mailbox -ResultSize Unlimited -Filter {ForwardingAddress -ne $null} | Where-Object {$_.ForwardingAddress -eq $RecipientCN}

But wait, we can get even faster! Why not search for the correct user right in the filter? Probably because it's hard to get the syntax right, because using variables in -Filter gets confusing.

The trick is to use double quotes around the entire filter expression, and single quotes around the variable:

$RecipientCN = (get-recipient johndoe).Identity
Get-Mailbox -ResultSize Unlimited -Filter "ForwardingAddress -eq '$RecipientCN'"

This version returns the same results in 0.6s - about 50 times faster.