[Mimedefang] Domain canonifying and RFCs
Marcus Schopen
lists at localguru.de
Sat Sep 24 17:50:26 EDT 2016
Am Donnerstag, den 13.10.2011, 10:57 +0200 schrieb Ernst du Plooy:
> I posted the following on the sendmail (comp.mail.sendmail) newsgroup,
> but I don't get any reaction. I realise this is not a mimedefang
> problem, but I'm sure some of you have also run into this issue.
>
> RFC 821 section 3.7 states "Whenever domain names are used in SMTP
> only the official names are used, the use of nicknames or aliases is
> not allowed.". This however changed in RFC 2821 section 3.6 where is
> states that CNAME RRs may be used.
>
> Currently Sendmail still rewrites the sender domain. Does this mean
> that the default behaviour of Sendmail is not RFC compliant or are
> there other RFCs that still limits the use of CNAMEs with MX records
> (maybe RFC 1034 section 3.6.2)?
>
> Thanks
>
> P.S. I know the setting confDONT_EXPAND_CNAMES will disable this
> behaviour, but I would prefer not to implement this. Also I cannot
> modify the DNS records since it is an external DNS server.
> They insist their DNS settings are RFC compliant.
>
> Their DNS records looks like this:
> c.domain.com IN A 1.1.1.1
> a.b.domain.com. IN CNAME c.domain.com.
> c.domain.com. IN MX 10 mail.domain2.com
> c.domain.com. IN MX 20 mail2.domain2.com
>
> user at a.b.domain.com will be rewitten to user at c.domain.com
Old thread, but I ran into the same problem on Ubuntu 14.04 LTS
(sendmail 8.14.4) today. Setting confDONT_EXPAND_CNAMES to True fixed
it. Shouldn't that be put to default sendmail.mc? Took me three beer to
figure out the problem, because I never looked into that dark corner.
Ciao!
Marcus
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