A customer of ours (thanks Kevin!) informed us of another way to send as a secondary alias the other day, so we thought we’d share. It’s a little more difficult to setup, and might not work in all environment due to firewall restrictions, but it doesn’t clutter up your GAL as the other method commonly used, described here:
So here’s the scenario. Let’s say you are an organization that does business as different names. The user Joe has aliases of firstname.lastname@example.org and email@example.com. Emails addressed to both addresses get delivered to the same mailbox. If the message comes into firstname.lastname@example.org you want Joe to reply as email@example.com. If the mail comes into firstname.lastname@example.org, you want Joe to reply as Joe@biz2.com. It seems simple, but in Exchange you can only send as the primary SMTP address on the account.
This solution is to create a POP3 account in Outlook for the secondary alias. You then configure the account to never check the mailbox (so POP3 doesn’t need to be enabled on the account), and it sends mail using the Microsoft SMTP server. It’s important to note that one limitation of this method is that it will only work if you domain is Authoritative in Microsoft Online, as you can’t use the SMTP relay servers until your domain is Authoritative.
First, you’ll need to configure all the POP3 settings in Outlook. For more information see:
Second, you’ll need to configure Outlook to not check the the POP3 account for mail. To do this click CTRL+ALT+S to bring up the Send / Receive Group settings, you can also get there by going to Tools->Send/Receive->Send/Receive Settings->Define Send/Receive Groups… Once there, click edit and then select the POP3 account and uncheck the box to receive mail items. This will prevent Outlook from checking the account.
Once everything is setup, you’ll be able to choose which alias you want to send as when sending email.