I am working on a program to filter out spam. I'd like the program to be run whenever new mail is received in my public e-mail box, and if it is acceptable, the program forwards it to a private e-mail box. I changed my .forward file to the following:
(the zvikabh is to keep a copy of the e-mail in the public e-mail box, and gigo.out is the filtering program.)
When I receive mail, I get a "returned mail: service unavailable" error e-mail from the mailer. The message contains the following lines:
sh: gigo.out not available for sendmail programs
554 "| gigo.out"... Service unavailable
and gigo.out is not run. Why is this happening?