Configuring Exchange Account Aliases in Apple Mail

January 8, 2016

If you've had the same email address for more than a few years, chances are the organization that runs your mail server has gone through a migration of some kind. Some common ones that I've seen:

• Domain migration: [email protected] to [email protected]
• Rebranding: [email protected] to [email protected]
• Status change: [email protected] to [email protected]
• Name change: [email protected] to [email protected]
• Updated naming scheme: [email protected] to [email protected]

The Problem

In each of these scenarios the server administrator should strive to have uninterrupted delivery of mail, meaning that mail sent to any of the accounts ends up in the same mailbox. These additional addresses are called aliases in Microsoft Exchange.

This setup is great until you try to Reply All to an email thread and end up sending a copy to yourself through an alias. Mail, Apple's email client on OS X (sometimes referred to as Mail.app) doesn't let you edit the alias list for an Exchange account. However, it happily supports aliases for POP or IMAP accounts, and we can use that foundation with a few tweaks depending on your Mail version.

The Fix

There are three workarounds to editing the alias list depending on which version of Mail you are using.

El Capitan (10.11)

This workaround is pretty easy and can be done entirely in the UI:

1. Open Mail's preferences with ⌘+, or in the menu bar under "Mail > Preferences"
2. Select the Exchange account in the list
3. Under the "Account Information" tab, note the current value of the "Outgoing Mail Server (SMTP)" dropdown
4. Temporarily update the value to "None"
5. Switch to the "General" preference tab, which should trigger a dialog to save the changes to your Exchange account
6. Click "Save"
7. Switch back to the "Accounts" preference tab, which should have an enabled Alias dropdown
8. Add your new alias addresses to the list
9. Revert the "Outgoing Mail Server (SMTP)" change to its original value
10. Switch to the "General" preference tab again, to trigger the save dialog
11. Click "Save"
12. No restart of Mail is necessary

Mountain Lion, Mavericks, or Yosemite (10.8 – 10.10)

Older versions require editing a property list used by Mail:

1. Quit Mail
2. Open /Users/{username}/Library/Mail/V2/MailData/Accounts.plist in a text editor
3. Search through the file for the EmailAddresses key corresponding to your Exchange account:

   	<key>EmailAddresses</key>
   	<array>
   		<string>[email protected]</string>
   	</array>

4. Add an additional entry in the array for each alias like so:

   	<key>EmailAddresses</key>
   	<array>
   		<string>[email protected]</string>
   		<string>[email protected]</string>
   	</array>

5. Re-open Mail

Mountain Lion (10.8) and older

These steps are the same as above with a slightly different structure in Accounts.plist:

1. Quit Mail
2. Open /Users/{username}/Library/Mail/V2/MailData/Accounts.plist in a text editor
3. Search through the file for the EmailAddresses key corresponding to your Exchange account:

   	<key>EmailAddresses</key>
   	<array>
   		<string>[email protected]</string>
   	</array>

4. Add a new key EmailAliases just below EmailAddresses like so:

   <key>EmailAddresses</key>
   <array>
   	<string>[email protected]</string>
   </array>
   <key>EmailAliases</key>
   <array>
   	<dict>
   		<key>alias</key>
   		<string>[email protected]</string>
   		<key>name</key>
   		<string>John Doe</string>
   	</dict>
   </array>

5. Re-open Mail