During a recent large Office 365 Hybrid Deployment, I came across the issue of many users (400+) having the ‘Automatically Update E-mail Address based on Recipient Policy’ option unticked. This meant that the users in question did not have the correct routing address of username@domain.mail.onmicrosoft.com specified. When attempting to migrate the mailboxes of said user accounts, they failed with the following error:

The target mailbox doesn't have an SMTP proxy matching 'domain.mail.onmicrosoft.com'

This address is required for mail routing between On Premise users and Office 365 users, therefore without if the mailbox move cannot take place. This address is added to all Email Address Policies which contain the hybrid domains during the Hybrid Configuration, in order to put the correct routing in place.

The company in question only had one email address per user in the format of firstname.lastname@domain.com so there was no reason not to have this option enabled. The only exception were a few users who had a different SMTP suffix (domain2.com), so these users needed to be left alone. The first thing I had to do was identify which users had the email address policy disabled. To do this I ran the following command:

get-mailbox | Where {$_.EmailAddressPolicyEnabled -eq $false} > C:\Temp\emailpolicy.txt

After realising there were 400+ mailboxes to enable this on, it became obvious that this was a problem which only Powershell could solve. Before I started, I first used the command listed on a previous blog http://doubledit.co.uk/2014/12/02/how-to-export-a-list-of-all-primary-smtp-addresses-and-aliases/ to export a list of all Primary SMTP addresses as a reference. I then ran the following command to find all users with a particular SMTP suffix and enable the ‘Automatically Update E-mail Address based on Recipient Policy’ option:

Get-mailbox | Where {$_.EmailAddresses -like ‘*@domain.com’} | Set-mailbox -EmailAddressPolicyEnabled $true

If you just wanted to apply the policy to all users, you would use the following command:

Get-mailbox | Set-mailbox -EmailAddressPolicyEnabled $true