admin- Go to Start > Run and type adsiedit.msc
- Now, find the unit where your AD user’s reside
- Right click the user you want to edit and click Properties.
- Find the variable proxyAddresses – this is the one you want to edit. When you add new e-mail aliases, you want to make sure that your primary e-mail address will start with upper-case SMTP. Your aliases, aka, secondary addresses should be lower-case smtp.