NOTE: Google Support note on this topic: https://support.google.com/a/answer/105694?hl=en
- Sign into the Google Admin console.
- From the dashboard, go to Apps > Google Apps > Gmail > Advanced settings.
- In the Organizations section, select the organizational unit for which you want to configure settings.
- Under POP and IMAP Access, select or clear the checkbox for Disable POP and IMAP access for all users in the domain:If you select the checkbox, POP and IMAP are fully disabled for all users in your domain.
- Users cannot access POP and IMAP settings in the Gmail interface.
- Users cannot access their mail via POP or IMAP even if they originally had it on.
- Users cannot access or search mail via Google Desktop (which uses POP).
If you clear the checkbox, POP is enabled for your users, but IMAP remains disabled.
- POP access is automatically turned on for your users.
- Users need to enable IMAP in the Gmail settings under Forwarding and POP/IMAP.
It may take 15-30 minutes for IMAP and POP changes to take effect. As long as the box is cleared, users can configure POP and IMAP access for a host of clients.