Open a new e-mail message and set it up the way you want it -- enter
recipients, set importance, set the sending account, etc.  Then, if the
Developer tab is not showing on the Ribbon, click the Office button (top
right corner of the message window) and click Editor Options at the bottom.  
In Editor Options, on the Popular section, check the box for "Show Developer
tab in the Ribbon".  Click OK to exit Editor Options.

Now click the Developer tab in the Ribbon.  Click the Publish button in the
Form section, then click Publish Form As....  In the Publish Form As box,
expand the Look In dropdown box and choose Personal Forms Library.  Give your
form a Display Name and/or a Form Name (I usually just use Display Name) and
click Publish.  Now your pre-filled form will always be available through
this library.  You can either add the Choose Form button to one of your
toolbars to easily get to the form, or you can click Tools | Forms | Choose
Form to do the same thing.

It sounds very complicated but it's really not, and if you do several forms
this way you'll get the hang of it very quickly.  I use a lot of pre-filled
forms this way.  Good luck and let me know if you have any problems.