Have a Galaxy S4 and use active sync to sync with my work Zimbra account (to my laptop and Outlook). No problems with email or contact. Calendar entries made into calendar on my laptop/Zimbra/Outlook transfers to phone with no problems. New Calendar entries that made on my phone does not transfer/sync to my laptop/Zimbra/Outlook. One weird point is that after I enter event into calendar on my computer/Outlook/Zimbra and it is transferred to my phone; if I then change something such as title of the event on my phone, this change will transfer back to my computer.