Google Message Continuity Setup and Administration Guide - Manual (Page 12)

Add Your Exchange Users to Google Apps 15
2. From the Google Apps control panel, click Organizations & Users in the top
blue bar.
3. From the Users tab, click Create a new user.
4. To add your users in bulk, click More actions, and then select the Bulk
upload users option. Create the groups (mailing lists) to match the mailing
lists in your Exchange Server (IMAP server).
Note that uploading a large number of users takes a long time. Once all users
are uploaded, you will receive an email notification. After about another 30
minutes, your users will be displayed on the Users tab on the Message
Continuity page.
Note: To add a large list of users in bulk, we recommend that you use Google
Apps Directory Sync (see “Adding Users with Google Apps Directory Sync” on
page 13).
Next Steps: Once you have added your Exchange users to
Google Apps, see “Change Your Settings in the Control Panel”
on page 17.