From: Tony Earnshaw (tonyebilly.demon.nl)
Date: Sun Oct 02 2005 - 08:02:43 CDT

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su den 02.10.2005 Klokka 12:54 (+0100) skreiv Stephen Carter:

> I understand that using square brackets around a host name tells
> postfix to not lookup the MX records for that host and simply use
> the A record instead, however I don't understand then why I should
> do the same when specifying an IP address. I would have thought
> an IP address is specific enough.
>
> Can someone explain this please?

Well, it depends on which IP addresses you're talking about. In main.cf
no IP addresses are specified in square brackets (apart from IPv6
addresses, which are always specified in square brackets, everywhere).

transport (5) (for example) says:

        The interpretation of the nexthop field is transport
        dependent. In the case of SMTP, specify a service on a
        non-default port as host:service, and disable MX (mail
        exchanger) DNS lookups with [host] or [host]:port. The []
        form is required when you specify an IP address instead of
        a hostname.

So, you have to let Postfix know that an IP address in a transport table
is an IP address by putting it in square brackets ...

--Tonni

--
Mail: tonyebilly.demon.nl
http://www.billy.demon.nl

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