Best or fast or easy way to authenticate to an MS mail server?

[TwoProc]

I'm having trouble getting mail out of the system to pagers, phones, etc. It "goes" out but I think it's rejected "out there" because it's an unauthenticated user to the exchange server (or whatever they're calling it right now at Microsoft). Can someone give me an example of a smbxxxxx (samba) command to authenticate (that is login) to the exchange server as an exchange user from the command line? Anyone have another idea on how to get this done in a better fashion than just something like:
cat fname| mailx 5551234567@somemesagingserver.com ?
Because this command just uses the forwarding rule(Dj rule if I remember correctly) in my mail configuration file, and sends it as the user that ran the command, not as an authenticated exchange user to our server. And it just doesn't work often beyond the internal server, and from a security standpoint, it's probably the correct in doing so.

Help appreciated.