I am postmaster@ a few places; I have absolutely no desire to provide a vehicle for spammers to (ab)use: I block 25/tcp from the network where my wireless APs live.
I wonder if you should block all port 25, or only port 25 to the nearest smart relay? Say I have a wifi AP connected to my NTL cable line. I ought to block the link to smpt.ntlworld.com because that will accept anything from me and hence anything from anyone using my WiFi. But I don't see a problem with them using an smtp server that they do have access to. The problem then is anyone sniffing will see they're connection and could use it unless they're using a non plain text authentication.
The real solution is for everyone running smtp servers to use authentication hidden by SSL including the main ISPs (such as NTL above). Then we wouldn't have to worry about this.
I know of one free hotspot in London that provides there own smtp server. And Boingo provide one as well but last time I looked it was authenticated but in plain text.
The last thought is that blocking port 25 completely will stop the use of STARTTLS which is the preferred way of supporting SSL. But you can still use SMTPS on port 465.
And finally, there is a now a market for email only ISPs. I know at least one person who runs hosted email only with SSL, authentication, pop3, imap, webmail and a spam control service. This plus a wires only broadband service is maybe all we need.
-- Julian Bond Email&MSM: [EMAIL PROTECTED] Webmaster: http://www.ecademy.com/ Personal WebLog: http://www.voidstar.com/ M: +44 (0)77 5907 2173 T: +44 (0)192 0412 433 -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
