One of the side effects of the recent outbreak of mail spread viruses is the suggestion from a few ISP's that they'll block their customers from using port 25. Personally, I think it's a great idea. People can still use the ISP's mailserver, and if they want to run their own server they have to either pay some extra sort of nominal fee, or register what they want to do in order to have the port unblocked.
This way the ISP would have a list of all IP addresses running mailservers, and could conduct regular anti relay checks on them - at the first sign of trouble, revoke their license to SMTP and be done with them. The suggestion of doing this was met with a lot of resistance from some people, however to be honest I suspect that those reacting have never had to run a company mailserver and deal with the amount of crap that comes through it - 90% of which is due to DSL / Dialup customers who don't know how to perform simple fucking preventitive maintenance on their own PC.
I'd welcome any change that would help get rid of log entries like these:
29/01/2004 07:04:18 p.m. SMTP Server: 219-88-47-114.dialup.xtra.co.nz (219.88.47.114) connected
29/01/2004 07:04:18 p.m. SMTP Server: 219-88-47-114.dialup.xtra.co.nz (219.88.47.114) disconnected. 0 message[s] received