Andrew McNamara --> info-cyrus (2007-04-26 16:16:49 +1000): > >if you check the domain "infoservices.in" with dnsstuff.com you can > >see no MX for that domain. > >But still mail is coming at user@xxxxxxxxxxxxxxxx we are using it for > >our official purposes and infoservices.in is our official site too. > > > >I wounder how mail is still coming with out MX ? could any one kindly > >explain ? > > Most Mail Transport Agents will fall back to the A record if no MX > records are found. This precident was set by sendmail, and woe betide > any implementation that ignores precident, but it would be foolish to > count on all MTAs behaving this way. With SMTP to you _can_ count on this behaviour. Quoting RFC 2821: 5. Address Resolution and Mail Handling [...] The lookup first attempts to locate an MX record associated with the name. [...] If no MX records are found, but an A RR is found, the A RR is treated as if it was associated with an implicit MX RR, with a preference of 0, pointing to that host. Regards, Jukka -- bashian roulette: $ ((RANDOM%6)) || rm -rf ~ ---- Cyrus Home Page: http://cyrusimap.web.cmu.edu/ Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
