this is how present Sendmail send looks like:

sub send {
    my ($class, $message, @args) = @_;
    my $mailer = $class->_find_sendmail;

    return failure "Couldn't find 'sendmail' executable in your PATH"
        ." and \$".__PACKAGE__."::SENDMAIL is not set"
        unless $mailer;

    return failure "Found $mailer but cannot execute it"
        unless -x $mailer;
    
    local $SIG{'CHLD'} = 'DEFAULT';

    my $pipe = gensym;

### print "| $mailer -t -oi @args";

    open $pipe, "| $mailer -t -oi @args"
        or return failure "Error executing $mailer: $!";
    print $pipe $message->as_string
        or return failure "Error printing via pipe to $mailer: $!";
    close $pipe
        or return failure "error when closing pipe to $mailer: $!";
    return success;
}
[download]

The added debug print line always returns string without any @args no matter how I passed them.