If you have access to the Google Apps administrator control panel you can stop nicknames and domain aliases from appearing in Google Contacts and your Global Address List. Doing this will also remove nicknames and aliases from any auto-complete email lists for your domain.
Once you are in the control panel follow the steps below:
- Click on Apps
- Click on Google Apps
- Choose Contacts from the Services menu
- Select Advanced Settings
- Select Hide aliases under Choose which user email addresses should be visible to other users
- Save changes
Note that “Changes to contact sharing options may not take effect for up to 24 hours.”
Let us know in the comments below if this Google Contacts tip works for you.