Uniformly, these security checklists focus on a lockdown approach. Encrypt everything, use only plain text, use only IMAP, ban personal email, disallow instant messaging -- you get the message. I'd like to suggest a novel approach: Incentivize company employees not to go outside the company prescribed methods of file transfer. In other words, make it easy and give them every reason to follow company policy.
 

For example, many employees -- especially the Gen X and Y -ers -- have at their ready disposal some combination of personal email account like Gmail or Hotmail, instant messaging, and Facebook and Twitter, or sometimes all of the above (me: guilty as charged). A company may try to prohibit use of these rogue communication channels, enforce best practices with punitive consequences, and even employ a technology to block employee access. However, like the protesters in Iran over the recent Presidential Elections who got the word out to the world over Twitter despite a government crackdown on traditional communications, people will find a way.
 

Now, let's take an opposite tack. Suppose you can provide a secure, encrypted solution that's integrated seamlessly with your email client so that the end user does not have to do anything complicated like pressing another button or compress files or certifying keys. Better yet, make it so that end users do not do anything differently at all than what they're used to doing: clicking SEND. And then incentivize end users from using other channels by enabling them to send files of any format and any size.
 

This is exactly the scenario that is possible for IT administrators who use the LeapFILE Desktop Suite that includes an Outlook plugin which eliminates the security and size limitations of Exchange. Achieve complete security with all carrot, and no stick. And end complaints and support tickets because of large files and blocked emails. Talk about having your carrot cake and eating it, too.