You can use g_virus_filter, but it doesn't act as a command line, instead it reads commands from stdin with the file name to scan..

Or for a simple command line g_filter_pipe.

Is there a way to pass incoming and messages to a command-line external filter? I’m looking for something like g_virus_cmd that doesn’t require a multi-part message and passes the entire raw message including all headers to the command line.

Thanks,
John