I had this problem on a Canon iR-ADV 4735 it allows you to set a Unit Name for the printer and if it has one set it sends the From header as 2 lines. For example:

From: "UNIT NAME" 
    <[email protected]>

It looks like the #findSender method in Mailer.ts only looks for the email in the line that begins with From: It does look like from RFC 5322 that long headers are allowed as long as they start with whitespace. I think just changing the parser so it unfolds the header before parsing by concatenating the extra lines if they begin with a whitespace would fix the issue.

To get around this we just cleared the Unit Name field so it was blank and the parser worked correctly. I also think setting the forceMailbox: in the yaml config would fix this as well if you didn't mind the sending address always being the same.