On Mon, Sep 9, 2013 at 6:36 AM, Graeme Fowler <[email protected]> wrote: > > The problem can be reproduced just using the "exim -bt" address testing > > mode. Please run "exim -bt [email protected]". The > > behaviour I have described results in Exim clearly showing the address > > rewrite as follows: > > > > [email protected] > > <-- [email protected]
I think it's a terminology issue. It's not exim "rewriting" the email address. I believe a more technically correct phrase would be "normalizing". A domain is not supposed to have an MX record set to a CNAME. Behavior when such an event occurs is undefined. Some MTA's merely fix the sending domain from the (invalid) CNAME to the (standards compliant) A record. I *know* sendmail does this as I'm a list owner on a mailing list machine which has this particular configuration. Read on for exim behavior in this scenario: > > You can see that the domain has incorrectly been changed to > > @www.bcidahofoundation.com - the correct behaviour would not include any Yes it has been changed, but no it's not incorrect (IMHO). > The domain *has not* been incorrectly changed. This is expected behaviour - > and it's all down to the DNS for that domain. > graeme@boom ~]$ dig bcidahofoundation.org any <snip> > ;; QUESTION SECTION: > ;bcidahofoundation.org. IN ANY > ;; ANSWER SECTION: > bcidahofoundation.org. 900 IN CNAME www.bcidahofoundation.com. > > ***Interesting bit here*** bcidahofoundation.org has no MX records, having > only a CNAME at the zone apex which goes to... ta-da! The explicit hostname > of www.bcidahofoundation.com. > So [email protected] gets internally rewritten in the envelope > to deliver to [email protected]. ...undefined behavior in this case means that the... > If you had MX records in the .org zone then you wouldn't see this - although > you can't have a CNAME and other data such as MX records at the zone apex, so > you'd need to fiddle with your zone a bit to correct that. ...domain gets changed because of the lack of MX record. Graeme pointed out a significant fact that I didn't piece together with all of the rest. Setting MX records to the CNAME doesn't do this address normalization, only if the domain name is a CNAME and there is not an MX record for that domain name. Personally I think that behavior (in both cases) should be configurable. Maybe it is and I just haven't delved into it. I don't use my system on domains without MX records so have never seen this behavior. ...Todd -- The total budget at all receivers for solving senders' problems is $0. If you want them to accept your mail and manage it the way you want, send it the way the spec says to. --John Levine -- ## List details at https://lists.exim.org/mailman/listinfo/exim-dev Exim details at http://www.exim.org/ ##
