>>> If I'm not mistaken, even properly configured MTAs will revert to the >>> A >>> record of a domain of there are no MX records available. (although I >>> haven't done any real research to back up this statement recently so I >>> could be completely off base) >>> >>> Alan >> >> That is known as the implicit MX and is held over from before the MX >> resource record existed. However, in my opinion, it has long outlived >> it's usefulness and now poses issues when a domain really doesn't want >> to have mail exchanged in their name. I've resorted to using an MX >> record of "0 ." for my domains that do not send or receive mail. This >> at least causes an immediate bounce and saves mail servers from >> connecting >> to a web server for 5 days. >> > >Uh, I think the way you're supposed to solve that problem (a domain >that doesn't receive email) is by: > >a) not having an MX record, >b) not having the hosts answer on port 25, or if they're shared among >multiple domains, have them refuse email directed at recipients of that >domain. > >(and, do correct me if I'm wrong: I thought MX records were optional; >you use them when you want email sent to some place OTHER than the >matching hostname; if you want email to go directly to a host, it's ok >to not have an MX record for that host) > >And, the way I handle not having anyone connect to port 25 on my web >server is ... my web server doesn't run any software on port 25. If >people are trying to send it email directly, and that email gets stuck >in their mail queue for 5 days because of it, that's their problem, not >mine.
In my case, it is a problem. Outbound mail sits in my queue for several days trying to connect to a server that isn't responding to connections on port 25. Whether it's a typo, or just plain a bad address, my users are only notified that delivery has been delayed. They still believe delivery is possible until the bounce shows up. It wastes resources attempting connections to a server that will never answer, and all because of the old implicit MX rule. I try to help everyone out on my domains that don't use e-mail by implementing an MX that will ensure an immediate bounce. I believe that all users would benefit from dropping the implicit MX rule from the RFC or if admins used a similar workaround as the one above. Jason
smime.p7s
Description: S/MIME cryptographic signature
_______________________________________________ NOTE: If there is a disclaimer or other legal boilerplate in the above message, it is NULL AND VOID. You may ignore it. Visit http://www.mimedefang.org and http://www.roaringpenguin.com MIMEDefang mailing list MIMEDefang@lists.roaringpenguin.com http://lists.roaringpenguin.com/mailman/listinfo/mimedefang