Newbie Question : EMail servers and MX records

Julien Matthieu julien at
Fri Jan 10 23:40:42 UTC 2003

i will try to answer you ...

paul williams wrote:
> Hi,
> I'm not too hot on DNS and that kind of thing. My understanding is
> that DNS is a globally connected list which allows host names to map
> to IP addresses.
> How does this work for mail servers using MX entries in the DNS ?
> For instance, we've got a small email server here which processes our
> email for xyz at I understand that theres a DNS entry for
> somewhere which points to our mail server.
> So, if someone, say xyz at sends a mail to me at, how
> does it all work. Does it search the DNS for an MX entry for
> and then direct it to our mail servers IP address ?

> Whys it called ? Or could it be
> just needs to be an MX entry ?
just need to be an mx record

> What happens if email sent is unable to connect to the IP address
> pointed at ? Does email get bounced ?
no, most if not all mail transport agent (servers) have timers to
re-try sending the email for a couple of days... so if it can't reach 
the mail server
after x times for let's say 2 days .... it comes back to the sender 
saying the mail server couldn't been reach...

finaly: i'll give you an example of this without the mail in

if you have any question ask ....

; <<>> DiG 8.3 <<>> mx
;; res options: init recurs defnam dnsrch
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 6
;;, type = MX, class = IN

;; ANSWER SECTION:          2H IN MX        10          2H IN MX        10          2H IN MX        10

;; ADDITIONAL SECTION:    2H IN A    2H IN A    2H IN A    2H IN A    2H IN A    2H IN A

;; Total query time: 86 msec
;; FROM: to SERVER: default --
;; WHEN: Fri Jan 10 18:37:51 2003
;; MSG SIZE  sent: 31  rcvd: 193

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