Sigh. Yes, you can't make stuff like that up.

I'm the CTO at Voltage, and I'm disappointed to hear that the original poster is having a poor experience with us. While I'm not going to claim the Voltage's gateway product is the ideal solution for every small business, we do feel like we do a great job helping businesses of many sizes that handle and exchange sensitive data comply with privacy requirements. There are a lot of security solutions that have been mentioned in this thread, ranging from GPG to SMTP over TLS. All of these solutions have value, depending on the problem that you are trying to solve. Our product focusses on encrypting email messages to end users without needing to enroll those users into a traditional certificate structure, and allowing those users to decrypt those messages with minimal difficulty. Regardless, I'd like to solve the original poster's problem. I'd ask that he contacts me at Voltage, and I'll handle any issue he's having at the moment.