The documentation is pretty specific about what you get back, but it might not be easily understood by the average Initiate. From Mail::Internet:

Body    The value of this option should be a reference
        to an array which contains the lines for the
        body of the message. Each line should be
        terminated with `\n' (LF). If Body is given
        then `Mail::Internet' will not attempt to read
        the body from `ARG' (even if it is specified).
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So, you get an array reference, which is kind of like an array, but isn't really one unless you "dereference" it. Otherwise, it's just a funny looking scalar that prints out as something like 'ARRAY(0x80f24a0)'.

        my ($body) = $message->Body();

        foreach (@$body) { }

        # Or, if you prefer:

        my (@body) = @{$message->Body()};

        foreach (@body) { }

        # Or, furthermore:

        my ($body) = join ('', @{$message->Body()});
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You would certainly want to read up on references.