Hey Mark,
There is no need to do intermediate builds you can update to the newest version from any version of SmarterMail. For example, you could go from SmarterMail 14 to 8664 if you wanted to.
I hope this helps.
Thank you,
Zach Sylvester
System/Network Administrator
SmarterTools Inc.
(877) 357-6278
www.smartertools.com