I haven't tried that for a while, but I don't remember there being a problem with using
multipart/alternative with quoted printable encoding.
That said, why don't you try dropping the encoding completely - MIME::Lite is very good at handling this stuff automatically.
So try this:
$msg = MIME::Lite->new(
To => $email_to,
From => $email_of_sender,
Subject => $email_subject,
Type => 'multipart/alternative',
);
$msg->attach(
Type => 'TEXT',
Data => $email_body
);
$msg->attach(
Type => 'text/html',
Data => $email_html
);
$msg->send;
Clint