Issue with S3 attachment

[weisisheng]

This code is a terrific practical example and runs flawlessly for me. The only issue is I get an error when opening the downloaded pdf. "Unable to open document. File type plain text document (text/plain) is not supported." I am a noob at Typescript but don't believe that has anything to do with it. If I go to the temp S3 storage bucket, the pdf opens as expected. So something is happening in the attachment phase out of the ordinary.

Appreciate any tips, tricks, trailheads....I've waded through the nodemailer docs to no avail.

*** it may not be related to this at all. I suspect it is a postmark email service transport layer I need to add. Will report back if I find something.