Usually, you have the output you want to mail in a variable, and then use code that is quite similar to the SYNOPSIS section of MIME::Lite to send the mail.

Basically instead of wherever you have print in your code, you could use

$output .= "whatever...";
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to append to the variable $output.

When you feel ready to send the mail, create the MIME::Lite object and send the mail according to the SYNOPSIS section of MIME::Lite, giving the Type as TEXT and the Data as $output.