OVERVIEW: Can Google Apps for Education email be managed by a separate email client
Yes. POP or IMAP Access is available. A list of available email clients and associated configuration settings is also available.
When configuring POP or IMAP access, be sure to enter in your full Google Apps for Education email address as the user name. For example, a user name would be firstname.lastname@example.org instead of wildcat.
For more information click here: https://support.google.com/a/answer/12103?hl=en