Quick Thoughts

Email Aliases in an Office 365 Environment Synchronized with Active Directory

These steps work if your Active Directory is linked to Office 365, either by Dirsync or the more updated Azure Active Directory Connect.

  1. Load up adsiedit.msc.
  2. Find a user object
  3. Get its properties
  4. Click on anything in the list
  5. Press P on the keyboard
  6. Scroll to "proxyAddresses" and edit it.
  7. Set the primary address as "SMTP:email@domain.com" (note the caps in the prefix)
  8. Set all alias(es) as "smtp:email2@domain.com" (note the lowercase prefix).

This can also be done using the Attribute Editor tab of the object in Active Directory Users and Computers.