This code won't work, as it doesn't actually send the message. To specify the method to send a message, you call send as a class method, but you still have to call it with the object to send as well, so in order to force it to send through sendmail, you would do this:

MIME::Lite->send("sendmail", "sendmail -t -oi -oem");
$msg->send();
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You can also call it without specifying the sendmail command as MIME::Lite->send("sendmail"); $msg->send(); and MIME::Lite will use it's default arguments to sendmail, which should be good for most cases.