If you are using with MspPortal Partners Barracuda Spam Filtering you can now do encrypt mail also at no additional cost.
Rackspace, Office 365, Google Apps, Exchange, Lotus Domino, GroupWise, Zimbra, Gmail, postfix, Send Mail, and more can be used as long as you can add a smart host entry.
I will assist in the original setup at no extra charge ( training) Use a word such as I do “secure” in the subject line plus you have the best spam filtering soluion in the industry.