Re: [exim] DNS MX records

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Author: Heiko Schlittermann
Date:  
To: exim-users
Subject: Re: [exim] DNS MX records
Tony Heal <theal@???> (Do 25 Jan 2007 22:51:07 CET):
> I am going to try and stand up a second email server. This server will start
> as a test server and then be moved into production. To begin with what I
> would like to do is set it up using the same email domain as my current
> email server and only have selected users ported over. Here are my problems
> with this.


Normally 2nd MX is meant as "fallback", having same authority as the
1st. From my understanding it's not easy to have a 2nd server just for
some users. (You could, but then you've to play with temporary errors.)

> 1.    DNS MX records - How can I have 2 email server? I already have a
> second and third email server set up for mail bagging set at priority 10 and
> 20. Can I set up a forth MX with a priority between the first(5) and
> second(10) at say 7? Will this cause emails to first go to the primary email
> server (5) then if a recipient is not found try the second MX record(7)? I
> am not real sure how all this works.


Normally servers are tried in order from lowest MX to hightest MX until
the message is accepted or refused. If the first refuses the take the
mail you cannot expect the second to be asked. From clients point of
view both have same authority.

If you reject the mail with 4xx then you next MX may be asked.

> 2.    related to the first but a little different. Is there any way on a
> debian Linux system using a very old version of exim (3.35) to have a system
> user with no email address, so that I can set myself up on the test email
> system, or do I have to simply forward my emails.


This question I do not understand. In the default config a system user
is a local user and this way it is a valid recipient. You can
:blackhole: or :fail: the address in some alias file, but I'm not sure
if this is what you want.


    Best regards from Dresden
    Viele Grüße aus Dresden
    Heiko Schlittermann
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