Does anyone have a working e-mail polling solution accessing through a VPN?

Our company only allows POP/SMTP access through the VPN. I installed Mergic, and am using Treo600 mail. The solution works flawlessly when I manually press the send/receive button. However, whenever I try to configure the treo to poll (e.g. every 15 minutes), the VPN connection is stuck on the connection screen and nothing will happen. Mergic acknowledges an issue with keylock on the T-600 in the release notes. However, the implication is that it should work if keylock is disabled. I tried both ways and this is not the case, the VPN fails even when keylock is disabled.

I'm looking for either a fix, or an alternate working solution of some VPN software and a mail-client.

Please do not suggest a desktop software solution, I have a laptop which is on-the-go whenever I am. An exchange-add-on server solution is similarly not an option at this time.