If you have an Enhanced mailbox, you can use ActiveSync, to not only sync e-mails, but also contacts and calendars.

You can log in to the GroupOffice Webmail and download a profile to automatically setup the e-mail as IMAP. The profile will include calendars and contacts if you have an Enhanced mailbox.

Here's the step by step for setting up an IMAP account on iOS.

Note that IMAP is preferred over POP. If you want to set up the account as POP, you have to set it up manually. IMAP is a protocol made to support several devices accessing one same account, with all folders synced at our server, which also guarantees that our backups will be executed.

Example setup for iOS: