On Sun, Oct 10, 2010 at 09:25:38PM +0100, Mike Cardwell wrote: > On 10/10/2010 19:41, Matthias-Christian Ott wrote: > > >> I recently got notified from a mailing list which is mangaged with > >> ezmlm that E-Mails could not be delivered because my mail server > >> rejected them. It turned out that the SMTP server or ezmlm itself > >> rewrote the recipient of the envelope from [email protected] to > >> [email protected], because example.com was a CNAME for b.example.com. > >> > >> Is such rewriting compliant with any standard (according to the > >> rejectlog no other E-Mails got rejected for this reason)? > > > > As more E-Mails come in, it seems very likely that some SMTP servers > > got confused by the CNAME and as far as I can tell from the logs > > didn't even try to deliver the E-Mails to my server. > > If your MX record is pointing at a CNAME, then your DNS is broken. MX > records are not allowed to point at CNAMEs, they're only allowed to > point at A records.
I think this was not the problem (maybe the problem statement was ambiguous). My DNS configuration was as follows: example.com. IN NS 198.51.100.1 example.com. IN NS 203.0.113.1 on the nameservers I had the following: example.com. IN CNAME b.example.com. example.com. IN MX 10 mx.example.com. b.example.com. IN A 198.51.100.2 mx.example.com. IN A 198.51.100.3 According to RFC 1912 there can't be other RRs if there's already a CNAME. It seems some SMTP servers followed the DNS RFC very closely and didn't send E-Mails at all. But this doesn't explain why that particular SMTP server rewrote the recipient (after I added a transitional MX record for b.example.com ebay.com did the same). Regards, Matthias-Christian -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
