On Tue, Sep 22, 1998 at 02:26:58PM +1200, Simon Blake wrote:
Over the weekend some fairly disreputable types in the US sent a whole pile of spam out with fake From: lines which resolved to a server I administer in Wellington. Since the hostname in question (city.wellington.net.nz) has no users and doesn't actually receive any legit email, my first response was to MX it to a spare IP# on our network so that I didn't have to deal with the many (~100K) bounce messages. Upon further reflection, in occured to me that an even better technique for avoiding traffic bills would be to MX city.wellington.net.nz to 127.0.0.1, which I did, and all my spam problems have gone away :-). My question - is this a dodgy thing to do, have I missed some critical reason why I shouldn't do this?
If no MX records exist, delivery via the A record will be attempted. If you don't need the A records, loose it and the MX records, that way, mail won't even attempt to be delivered. Having MX records, IMO implies the domains is `mail-connected' and therefore postmaster(a)city.wellington.net.nz should be a valid reachable email address (RFC requirement): --- RFC1123: Requirements for Internet Hosts -- Application and Support 5.2.7 RCPT Command: RFC-821 Section 4.1.1 A host that supports a receiver-SMTP MUST support the reserved mailbox "Postmaster". The receiver-SMTP MAY verify RCPT parameters as they arrive; however, RCPT responses MUST NOT be delayed beyond a reasonable time (see Section 5.3.2). --- Using 127.0.0.1 might cause mailer loops and other evils at remote sites (depending on their setup and other stuff). At the very least, it will generate for some sites postmaster double-bounces... -Chris P.S. 127.0.0.1 is an excellent way to fix horrible ad.banners - have a local DNS entry for ad.doubleclick.net or whatever to this address and you'll get nice fast speedy broken images. With more effort - you can replace them with your own adds, better still, the proxy can be made to recognize certain file types and modify them on the fly to swap out foreign banners with your own. --------- To unsubscribe from nznog, send email to majordomo(a)list.waikato.ac.nz where the body of your message reads: unsubscribe nznog