$attached is a hash reference so you need to dereference it, and default to an empty hash ref if $code is false:

my $attached = ($code) ? "attach_path => '$file_name',attach_filena +m
+e => '$file_name',attach_type => 'application/txt'," : {};

my $success = email( {
    to              => $email,
    from            => $from,
    from_name       => $name,
    subject         => $subject,
    body            => $body,
    %$attached
} );
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Update: as pryrt points out, $attached is not a hash reference (it is a string) but can easily be made into one - see my further example below.