It sounds like you already have the ability to drag a file into your DocMgmt software, so that’s not what you’re requesting. It looks like you might be using a distribution list to send the same identical email to a bunch of people.
I think you request is for an automatic way for every email you send to be placed in a windows folder as a separate file, so that subsequently you can drag these files wherever they need to be archived.
Is that right?
If so, are you asking for one file per email, or one file per recipient per email?
I am thinking that it would easier to have the program that generates the form letter also create the temporary files, but maybe you are also trying to prove that the email was sent.