I'm using the Putty portable client, so it's on a USB drive. The both the File and the Program is located in F:\PuTTYPortable folder which is where I would run the program.
If you don't mind using Perl, you can download and install Perl MIME::LITE and use that.
The link includes some sample code. Last time I looked the module had not changed
in awhile. But the code works and it is easy to use.