There are two flavors of the Full Version:
- The Pro version is the real deal! All the features you need, unlimited use for one single user. If you want multiple (unlimited) users in you company to use the software, please buy the Enterprise version.
- The Enterprise version has the same features as the Pro version, to be used by an unlimited number of users at your company. If just one person is going to use the software, buying the Pro version will be cheaper (both versions have the same features).
Other than that, both flavors have the same features (multiple recipients in To, CC and BCC, adding attachments, High/Low priority, etc.)