Richard.....
Apologies, not quite at your level; getting a bit out of my depth.
Test exactly as per above; didn't set any program.
Bizarrely, I can't now recreate the test. No problem with the standard '.txt', but as regards the '.pif'.....
AOL information box indicates:
"This file could not be sent. Please check to see if the file is open in another application" Not that I can see. .....?