Guys,

I'm stuffed.

I had Postfix running on the server for months. But all over sudden it stopped sending emails to extarnal domains. I must fix it, but I run out of ideas. PLEASE, HELP!

Here is my sad story.

Emails are Ok on the way from client app to my server. They are actually being stuck in the queue as deffered.

So, I have checked logs:
Code:
Aug  6 22:01:50 www postfix/smtp[3592]: 4F0272264CF3: to=<somemail@examplemail.com>, 
relay=none, delay=386320, delays=386264/0.06/56/0, dsn=4.4.3, status=deferred 
(Host or domain name not found. Name service error for name=mamail.com type=MX: Host not found, try again)
"Host not found, try again" looks like it is a DNS issue.

O'Reilly postfix definitive guide says: "The DNS query produced no answer. Either the DNS server is not reachable, or it is broken." It seems to be reasonable.

So I have checked /etc/resolv.conf :
Code:
www:/etc# cat /etc/resolv.conf
domain croup.de
nameserver 208.84.145.233
nameserver 208.84.145.155
nameserver 208.77.96.36

Then I checked  whether rimary DNS server is working:
www:/etc# man nslookup
Reformatting nslookup(1), please wait...
www:/etc# nslookup
> server 208.84.145.233
Default server: 208.84.145.233
Address: 208.84.145.233#53
> set q=mx
> googlemail.com
Server:         208.84.145.233
Address:        208.84.145.233#53

Non-authoritative answer:
googlemail.com  mail exchanger = 10 alt2.gmail-smtp-in.l.google.com.
googlemail.com  mail exchanger = 50 gsmtp147.google.com.
googlemail.com  mail exchanger = 50 gsmtp183.google.com.
googlemail.com  mail exchanger = 5 gmail-smtp-in.l.google.com.
googlemail.com  mail exchanger = 10 alt1.gmail-smtp-in.l.google.com.

Authoritative answers can be found from:
>
and also

Code:
www:/etc# dig mx googlemail.com

; <<>> DiG 9.3.4 <<>> mx googlemail.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 39960
;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;googlemail.com.                        IN      MX

;; ANSWER SECTION:
googlemail.com.         598     IN      MX      50 gsmtp183.google.com.
googlemail.com.         598     IN      MX      5 gmail-smtp-in.l.google.com.
googlemail.com.         598     IN      MX      10 alt1.gmail-smtp-in.l.google.com.
googlemail.com.         598     IN      MX      10 alt2.gmail-smtp-in.l.google.com.
googlemail.com.         598     IN      MX      50 gsmtp147.google.com.

;; Query time: 1 msec
;; SERVER: 208.84.145.233#53(208.84.145.233)
;; WHEN: Wed Aug  6 22:08:01 2008
;; MSG SIZE  rcvd: 163

www:/etc#
SO, it seems that my server's DNS is working fine! (or not?)

I even restarted postfix just in case.

Now what do I have as a result:
- postfix is up and running;
- postfix accepting emails;
- ostfix sends email to localdomains;
- DNS seems to be working fine;
- and IT DOES NOT SEND EMAILS TO EXTERANL DOMAINS!

I'm really, really confused.

Please, help!

Many thanks in advance!