Several of the modules in that thread are by RJBS, who has additional modules that can handle attachments, such as Email::Stuffer. Untested, but try something like this instead of the Email::Simple code in that thread:

Email::Stuffer
    ->from($smtp{user})           ->to($smtp{to})
    ->subject($smtp{subject})     ->text_body($smtp{body})
    ->attach_file('example.txt')  ->transport($transport)
    ->send;
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