Im not using it yet Gordy, just thinking about it.
I want to look into this a lot more before spending the $180 on HiveMail and then not using it.
I have read a bit about it now and I have seen a good few things about Horde, just editing it a bit can make it just as good, cleaning it up a bit more with another skin would probably also help

I always use Horde for my webmail now, havent used SquirrelMail or...hmm dont even remember the name now, but the other main free mail script.
Always do the /webmail login but go straight for Horde.
I would be interested in doing something like this but its something that might require a little bit of reading up on