Plug-in error when opening Apple Mail

Every time I open Apple Mail on my MacBook Pro with Snow Leopard Operating System, I receive an error message that Mail has disabled the following plug-ins: ProxiMail. Please see the attached screen shot.
When I click OK, Apple Mail loads and everything works properly. I would like to stop this error message from displaying. How do I disable the plug-in permanently or delete it? I don’t know if I want to get a new version yet.
Incompatible Plug-ins Disabled Mail has disabled the following plug-ins:
ProxiMall
Contact the makers of these plug-ins for versions that are compatible with Mail 4.1 and Message 4.1.
OK
