Update: Ok, I've read your question a little more carefully, and realize that you are only having problems with MS Outlook, so maybe this doesn't apply. Still, my recollection is that MIME::Lite is not what I call 'Unicode clean' - you need to pass it a byte string that contains the message encoded in the desired character set.

Original response:

I bet $content contain code-points and not a UTF8 byte stream. Try this:

use Encode;

my $msg = MIME::Lite->new(
  ...
  Data => encode('utf8', $contents),
);
[download]

My recollection is that MIME::Lite doesn't perform any character encoding of the message even when you specify the content-type.charset attribute.