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    SubjectRe: DNS goofups galore...
    kaih@khms.westfalen.de (Kai Henningsen) writes:

    >hps@tanstaafl.de (Henning P. Schmiedehausen) wrote on 12.02.01 in <968mjv$l9t$1@forge.intermeta.de>:

    >> jan.gyselinck@be.uu.net (Jan Gyselinck) writes:
    >>
    >> >There's not really something wrong with MX's pointing to CNAME's. It's
    >> >just that some mailservers could (can?) not handle this. So if you want to
    >> >be able to receive mail from all kinds of mailservers, don't use CNAME's
    >> >for MX's.
    >>
    >> No. It breaks a basic assumption set in stone in RFC821. It has
    >> nothing to do with mailer software.

    >May I point out that RFC 821 does not mention either CNAME or MX anywhere.

    RFC 974 is about the "DOMAIN NAME SYSTEM". RFC 821 mentions DOMAINS:

    3.7. DOMAINS

    >So don't tell us about stuff set in stone in RFC XYZ, when it's plain
    >you've never looked at that RFC.

    Says who? RFC974 is a clarification of how to interpret Domain Name
    System contents in a mail context. RFC821 makes a clear statement about
    Domains in section 3.7:

    [...]
    Whenever domain names are used in SMTP only the official names are
    used, the use of nicknames or aliases is not allowed.
    [...]

    and in RFC974 it is stated:

    [...]
    In addition to mail information, the servers store certain other
    types of RR's which mailers may encounter or choose to use. These
    are: the canonical name (CNAME) RR, which simply states that the
    domain name queried for is actually an alias for another domain name,
    which is the proper, or canonical, name; [...]
    [...]

    In my understanding (and I assume that you're familiar with both as
    you've chosen to insult me by suggesting that I've not read this
    stuff), this means clearly:

    "YOU MUST NOT USE AN ALIAS WHENEVER DOMAINS ARE USED IN SMTP". (RFC821)

    and

    "THIS NAME IS AN ALIAS FOR ANOTHER DOMAIN NAME, WHICH IS THE PROPER,
    CANONICAL NAME".

    This boils down for me to

    "YOU MUST NOT USE A CNAME ANYWHERE IN SMTP".

    and "ANYWHERE" also states for me "in the 220 greeting".

    Any further questions?

    Regards
    Henning
    --
    Dipl.-Inf. (Univ.) Henning P. Schmiedehausen -- Geschaeftsfuehrer
    INTERMETA - Gesellschaft fuer Mehrwertdienste mbH hps@intermeta.de

    Am Schwabachgrund 22 Fon.: 09131 / 50654-0 info@intermeta.de
    D-91054 Buckenhof Fax.: 09131 / 50654-20
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