Large events from devices Pending server Processing

Hi all:
We have a GMS 2.1 build 230 server with 179 users and 172 devices in 10 POA with GW2012 SP4 and our users receive email in their devices but when they try to send an email it disappears from the device but never reaches GW.
Our server GMS server has 350.000 Events from Devices Pending Server Processing in dashboard. We have tryied to vacuum DB, performed regualr maintenance tasks, opened an SR, but still stuck with the problem for one week.
Is there any way to purge those pending events.
Any help will be appreciated.
Thanks in advance.