The Zimbra Network Editions include EAS or Exchange Active Sync support.

The Zextras add-on package also adds EAS support to the Zimbra Open Source Edition.

Our public Zimbra server has mobile support using the Exchange ActiveSync protocol (EAS) with 'push' notifications.

EAS will sync:

• folders
• mail
• contacts
• calendars
• tasks

All modern iOS devices support 'Exchange' or 'EAS' accounts without installing any apps.

https://support.apple.com/en-us/HT201320

This was done using iOS 8.1.3

On your iOS device, add a new Exchange/EAS/Corporate account for the new server.

1. Tap Settings
   
   
   
2. Scroll down, tap Mail, Contacts, Calendars
   
   
   
3. Tap Add Account
   
   
4. Tap Exchange
   
   
   
5. Enter your Email address, Password and a Description and tap Next
   
   
   
6. Enter Server zimbra.virtualarchitects.com
   
   
7. Leave Domain blank
   
   
8. Use your full email address as username
   
   
9. Enter your password
   
   
10. Tap Next
    
    
11. Tap Save