Exchange – Bulk-add forwarding addresses

There's not many circumstances where you'd want to set forwarding on lots of mailboxes at once - but if you're in that situation (perhaps you're moving mailboxes to a Cloud mail provider)  it's useful to know that it's fairly straightforward and can be accomplished with a little PowerShell.

In the example below, we're assuming that your on-premise Exchange 2007/2010 domain is contoso.com and all your mailboxes are in the Staff OU.

The Cloud provider you're moving your mail to will eventually take over the MX record for your domain, but will also accept mail to each user's Username@cloud.contoso.com. We'll keep mail contacts used for the forwarding in the OU CloudContacts.

To accomplish this, we quite simply need to get the mailboxes in the specific OU, create a mail contact for each one (with the external email address they will use on the cloud provider's domain) and then set the forwarding address on the mailbox:

# Loop though the object returned by Get-Mailbox with each element represented by $mailbox

foreach ($mailbox in (Get-MailBox -ResultSize Unlimited  -OrganizationalUnit contoso.com/Staff)

{

# Create the forwarding address string
$ForwardingAddress= $mailbox.SamAccountName + "@cloud.contoso.com"

# Check there isn't a contact, then add one

If (!(Get-MailContact $ForwardingAddress -ErrorAction SilentlyContinue))

{

New-MailContact $ForwardingAddress-ExternalEmailAddress $ForwardingAddress- OrganizationalUnit contoso.com/CloudContacts
}

# Set the forwarding address
Set-Mailbox $mailbox -ForwardingAddress $ForwardingAddress

}

Of course, that's a fairly simple example.  What if the email addresses at the cloud provider don't match the Windows Logon ID or anything else that is an attribute of the Mailbox? Well the simple solution is to use something like a CSV file containing a mapping between an attribute on each Mailbox and the external email address for that user:

SamAccountName,ForwardingAddress
jamesw,jimbo@cloud.contoso.com
philipg,phil@cloud.contoso.com

In this example, we'll save that file as input.csv and use that as are input to the foreach loop. Again CloudContacts OU will contain our new mail contact objects:

# Loop through the object returned by Import-Csv with each element represented by $person

foreach ($person in (Import-Csv .\input.csv))

{
# Check the Mailbox for the person exists
If ((Get-Mailbox $person.SamAccountName))

{
# Check the mail contact doesn't exist and if not add it
If (!(Get-MailContact $person.ForwardingAddress))

{

New-MailContact $person.ForwardingAddress -OrganizationalUnit contoso.com/CloudContacts
}

# Set the Forwarding Address on the Mailbox
Set-Mailbox $person.SamAccountName -ForwardingAddress $person.ForwardingAddress
}

}

Word of caution - it's worth (as always) running these commands in your test environment first - and of course consider appending -WhatIf to the New-MailContact and Set-Mailbox commands to check they'll do what you want in your production environment.

Hope this helps,

Steve