Although I'm not an expert on PAR, I still suspect it has something to do with all those use lib dirs. I suggest you inspect all of the directories listed in @INC when the program runs (e.g. print "<<$_>>\n" for @INC;) for which versions of Email::Sender etc. are installed there. Also, I would suggest just removing all of the use lib dirs from the script, as I don't see a good reason why all the C:\Strawberry ones are there in the first place (and "C:\\Strawberry\\perl\\vendor\\lib\\Email" is almost certainly wrong), and just working with Perl's defaults - that's what cpanm will use as well.