I think you are posting on the wrong place... This is XDAI and II forum... :wink:
However I can answer part of your question:
The SE P900 uses a proprietary email client, which is not bad at all...
For the other question I would suggest you to visit:
and search for that application there...
and also visit http://www.howardforums.com
for some great forums about SonyEricsson P900...
My Current Devices: Samsung Galaxy Note (International Version), Nokia Lumia 900, (backup), Motorola Atrix 4G (GB 2.3.4)*sold*, Motorola Lapdock *sold*, Asus Transformer Tablet, Nexus One Google Phone (retired), Viewsonic G Tablet (retired), Nokia N97 40 Gb *sold*, Nokia 5530 *gave it away*, HTC Touch*died*, HTC Touch Diamond GSM*sold*, Palm Pre GSM*sold*