You shouldn't have to do much to move the installation. I have used this when traveling and it's easy to go back and forth. If you duplicate the folders from your hard drive on the USB drive, it'll work without a hitch. For example: I created '\Program Files\pmail' and '\data\mail' on the USB drive to mirror the setup on the hard drive. Then, just start pmail instance from the USB drive with the -ROAM option and it should find everything just fine. ROAM tells pmail to ignore the drive letter in paths so it isn't dependent on a specific drive letter to work.

 If you are dead set on changing the folder structure, you can change your mailbox path using pconfig.exe (found in the pmail program folder). You should also search for all instances of your old folder names in the pmail.ini file (in the mail folder) and change them to the new folder names. You will still need to use the ROAM option to run from the USB because the drive letter may vary from one system to another.
 

I have Pmail working the way I want on my laptop, merging all the old emails from all my computers.   Not wanting to get out of sync again I would like to move to a USB-stick based implementation that I can carry from one computer to another.

On the laptop I have the Pmail program in C:\Program Files\PMAIL and the actual MAIL folder somewhere else.  If I had thought about this I would not have done it that way.

So how do I move the program files and MAIL folders to a single directory tree on the stick such that PMAIL can find the mail directories, etc?  I assume that somewhere in one of its configuration files is the name of the directory path to the mail files that I wikll need to adjust.