SYMPTOMS

ActiveSync devices occasionally loose synchronisation and require the resynchronisation of folder data from the server to the device.

CAUSE

The ActiveSync protocol supports a number of methods for notifying changes between the server and the client.

Most devices (inclusing the Samsung S3 device) make a hanging request to the server (typically called "Push"). A "Push" request is held open until a timeout limit is reached or a change is made on the server.

If there is a communication failure between the client and the server whilst a hanging request responds with changes, then the synchronisation state between the client and the server will no longer be valid.

In this case, the client and server detect the invalid state and will resynchronise the contents of the folder.

If a mobile device toggles between carrier and wifi networks, it is possible that a push Synchronisation request may be interrupted.

SOLUTION

There are no configuration changes that can be made to the MailEnable server to overcome the issue (principally because the problem is occuring in the client/server communication network).


Here are some suggestions:

1. Change the accounts on the devices so they only Sync the objects/folders that are required.
ie: don't sync tasks, SMS, contacts for a mailbox unless you actually need the data.

2. If the network is unreliable, consider changing the Sync schedule settings to poll rather than using Push.
(using Push means that a connection is held open between the client and the server, meaning that if a dropout occurs, the device will loose its sync state).

This invariably means that the contents of the folder then needs to be drawn from the server again. A reasonably setting to use here would be to poll every 5 minutes.