On 05/29/2011 01:50 PM, Ronald MacDonald wrote:
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Hello,
Just been having a look through my config. I've an obscure case, where I've
added a domain to the alias/lookup tables but the customer has not yet changed
her DNS settings.
In this case, when I'm waiting for a client to update DNS, I still need to be
able to get in touch with them. It looks like I've done something funny,
whereby Postfix does not look up DNS MX records for domains it considers
'local'. First of all, would it be advisable to try and change/update this so
that DNS is referred to for each and every email, even on local delivery and
second of all, if this is the case, where would I be advised to look in config
to make this alteration?
Wherever this is applicable, putting a hostname or domain name inside
square brackets prevents an MX lookup.
mail.example.com : look up MX record for mail.example.com; if this
exists, look up the A record for the MX; if this does not exist, look up
the A record for mail.example.com
[mail.example.com] : look up A record for mail.example.com.
mydestination = mail.rmacd.com, localhost
This does not cause DNS lookups, because postfix handles the domain
itself, so there is no reason to do a DNS lookup.
HOWEVER, relaying the mail to its destination does cause postfix to look
up the destination's MX record (if any).
In general, no MX lookups are done when receiving mail - except when
explicitly requested via restrictions such as check_*_mx_access.
Lookups for MX records are done when delivering mail; show logs where
the behaviour occurs and somebody might be able to help.
--
J.
