office 365 logo

In Office 365 Exchange Online you may create an alias on a user in order to “translate the username better” e.g.

for the user might not make sense and mabye the name somehow does not Sync correctly which could make it hard to find the user.
Add an Alias:

When you share files you may look up the alias in the search dialog Box like this:

Alias and username

You add an alias in the Exchange Online Control Panel.
Select the user and click Edit Exchange Properties
Select E-mail Properties
Click Pluss
Enter the prefered alias like;
Make sure SMTP is selected
Check the Make this the default reply address
Click Save and wait for the changes to propagate on the account

SMTP  mailbox alias