resync when send mail on android device


we are using GW 2012 SP2 with Mobility Service 2.0.

Everything is fine but when a user sends or replies to a mail from his mobile device (Samsung Galaxy S4, Android 4.3), his complete data gets resynced. (mail, contacts and calendar)
I completely resetted the device in Mobility console but its the same issue after doing that.

has anybody ever seen this??