A simple how to on how to make simple mail "almost" standalone
uses, you might ask?
default email perhaps?
why not just download Thunderbird you might ask, because then what would be the fun in not learning how to do something new...

anyway,
first step is to create the Firefox shortcut on desktop, or in the program files (location listed below) or wherever you put it, this can be done by using the existing shortcut and right click Firefox icon then create shortcut.

Next, you will need to right click the Firefox shortcut you just created and click properties
go to the find target area and replace what is already on the area that says target with this
"C:\Program Files\Mozilla Firefox\firefox.exe" -chrome "chrome://simplemail/content/main/main.xul"
unless you replaced the Firefox folder with a different one, but I can't tell you where you put your folder, so just replace the stuff before -chrome with whatever is on your computer.

what this should do is give you a simple mail only window.
next all that is needed is a rename, and maybe a icon change if you already know how or really want to but since I already did what I set out to do. it does not matter to me, so no icon creation guide.

Update: some small issues with it not detecting any information from your profile, because it needs Firefox open or something.
so until a method becomes official, this is a pretty crappy method.