I'm using exim4 with a catchall router to forward mail to a java process. The java process users are the valid recipients. I'm trying to reduce the amount of spam routed to the java process by whitelisting the users in exim.
I have tried this in my config file:
acl_check_rcpt: deny message = invalid recipient domains = thedomain.com recipients = !/etc/exim4/recipients_whitelist
Along with about a billion other things. I have verified that if I rewrite the condition as just
deny recipients = email@example.com the message is rejected but I cannot get the whitelisting approach to work. I have also tried inverting the logic to accept the whitelisted users but that does not work either.
Here is my router:
outer_catchall: driver = accept transport = dev_null_transport