Hi everyone. I'm thinking of a kind of unusual setup and I was hoping for pointers. I want to set up a gateway to limit email outbound. I've found lots of documents about limiting inbound, but not much on limiting outbound. Here's my story.
I'm a sysadmin at a community college. I have a number of web servers and lots of users who write incompetent CGI mail forms. After having two of my servers blacklisted as spam relays, I wised up and blocked SMTP outbound at the firewall. I allow email to the district email server (not run by me), again with simple port block/allow rules on the firewall. Student email is hosted on google apps. If I allow uninspected STMP to google's email servers I'll still be a nice target for spammers. I also have a few other email addresses I'd like to send email to, like my cell phone's SMS email address etc... So, I want to set up an outbound only SMTP gateway which only allows email to 1) the student email domain (seattlecentral.edu) 2) other addresses I specify 3) possibly other things I haven't thought of yet and I also want to drop any attempts to send millions of emails, in case I screw up the by-address filters. Again, this server should allow no inbound email at all. This is purely to allow CGI and other automata to contact a limited set of external email addresses. I've found some postfix docs describing similar things for inbound, but not outbound. I haven't started actually experimenting yet, so I don't know if this is a silly idea, or what. (Hence the email to this list.) So, any advice would be wonderful. Pointers to useful docs would be superb. If there are any good search terms I might use while googling for this kind of thing, that would also be helpful. -- Thanks! Dylan Martin Network Admin Seattle Central Community College
