I’m not sure this affects the newest version of MIME::Lite; however, if you find that you are having issues with your messages being rejected or marked as spam, due to an internal host being added to the Return-Path, the following fix might work for you.
Rather than using:
my $ml = MIME::Lite-new(
From => ...
To => ...
...
);
$ml->send();
Use the following:
$ml->send_by_sendmail(SetSender => 1);