Heavy mail users

We have a few users that receive 100+ emails daily.

These users seem to experience issues with email synchronization stopping. Our workaround is to teach them how to delete and recreate their connection to the DS then mail flows again.

We are testing several mobile devices as we suspect it is poor phone performance causing the issue.

Does anyone know of any DS limitations for mail volume that could contribute to the issue.

Let me know

Thanks
Christa