rblsmtpd(1) on Linux
The text 58c13791a88a, as Debian 9 (Stretch), Debian 8 (Jessie), Debian 7 (Wheezy), Debian 6.0 (Squeeze), Debian 5.0 (Lenny) shipped it.
blocks mail from RBL-listed sites. It works with any SMTP server that can run under tcpserver(1)
Flags it lists
-
-B -
-C -
-a -
-b -
-c -
-r -
-t