Mass Email Program

Does anybody know of a good bulk email program for OpenSUSE 13.1? I have about 1,500 clients I would like to email regularly with some pretty HTML emails. I know I could just use Kmail or Thunderbird, but those aren't really designed for this. And no....I'm not a spammer.

Thanks!

Rudy Hartmann
rudy@rocktechnology.biz

:)