>> My understanding of why CNAMEs are prohibited for MX hosts is that they can >> introduce loops. The last paragraph of Section 5.1 explains how a sender >> should attempt to locate itself in the list of MXes, ordered by preference. >> You may want to compare that paragraph with the historic discussion in RFC >> 974, >> which, under "Minor Special Issues", says:
On 22.01.15 09:06, Jeff Potter wrote: >The other issue: a sending server can resolve the CNAME and rewrite the >address on you. I saw this years ago. > >E.g.: > >foo.com with a CNAME of “bar.com” >foo.com with an MX of “some-good-mailserver.example.com” > >Sending email to “j...@foo.com” resulted in an email to “j...@bar.com” — the > sending MUA / MTA resolved the cname on me. (I think it was qmail at the > time.) I've seen this, seems it's described in RFC 1123, section 5.2.2. However, it's a different issue. Still, NS and MX must not point to a CNAME. -- Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/ Warning: I wish NOT to receive e-mail advertising to this address. Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu. Windows found: (R)emove, (E)rase, (D)elete ------------------------------------------------------------------------------ New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. http://p.sf.net/sfu/gigenet _______________________________________________ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
