Re: [Exim] Address canonicalization

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Autor: Philip Hazel
Data:  
A: Foster, C.
CC: 'exim-users@exim.org'
Assumpte: Re: [Exim] Address canonicalization
On Tue, 20 Jul 1999, Foster, C. wrote:

> It would appear that exim does not
> canonicalize domains in addresses when it finds a CNAME.
> Is this true? If so, why is it so, when RFC 1123 states:
>
>    5.2.2  Canonicalization: RFC-821 Section 3.1

>
>    The domain names that a Sender-SMTP sends in MAIL and RCPT
>    commands MUST have been  "canonicalized," i.e., they must be
>    fully-qualified principal names or domain literals, not
>    nicknames or domain abbreviations.  A canonicalized name either
>    identifies a host directly or is an MX name; it cannot be a
>    CNAME.

>
> I'm not saying that I think exim *should* do this - I don't
> see a good reason for messing about with recipient addresses.


I think (a) I'd overlooked that and anyway (b) I agree with you. I don't
see a good reason for messing about. I do agree that people should not
set up their DNS to use CNAMES for mail; MX records provide the
indirection facility, and CNAMES just make more lookup work. However, if
a CNAME is encountered, it seems reasonable to do something sensible
with it.

Exim will canonicalize nicknames.



-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.