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   This isnt really related to SPF, i apoliogise for that.
Since this is a forum with mega expertise in the area of mail servers and their setup, i post my question here.
One of our customers is giving me a lot of grief since none of our users seem to be able to send them emails.
Our mail system cannot connect to their exchanger for some reason (host unavailable error), but when i do an mx-record lookup it seems all allright to me, except maybe their entry for their 2nd nameserver. (i've never seen such entry before, but i'm no expert)
mx quesry on their domain:

Header:
ID=24159, QR=Response, Opcode=QUERY, RCODE=NO ERROR
Authoritative Answer=No, Truncation=No
Recursion Desired=Yes, Recursion Available=Yes
QDCOUNT=1, ANCOUNT=2, NSCOUNT=3, ARCOUNT=4
Question:
Name=*their domain name*, QTYPE=MX, QCLASS=1
Answer Section:
- Name=*their domain name*
Type=MX, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=20
Preference=10, Mail Exchange=mxa.mail.*their ISP domain*
- Name=*their domain name*
Type=MX, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=8
Preference=10, Mail Exchange=mxb.mail.*their ISP domain*
Authority Records Section:
- Name=*their domain name*
Type=NS, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=16
Name Server=ns2.*their ISP domain*.net
- Name=*their domain name*
Type=NS, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=6
Name Server=ns3.*their ISP domain*
- Name=*their domain name*
Type=NS, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=6
Name Server=ns1.*their ISP domain*
Additional Records Section:
- Name=mxa.mail.*their ISP domain*
Type=A, Class=1, TTL=33 (33 Seconds), RDLENGTH=4
IP Address=xxx.xxx.xxx.xxx
- Name=mxb.mail.*their ISP domain*
Type=A, Class=1, TTL=18 (18 Seconds), RDLENGTH=4
IP Address=xxx.xxx.xxx.xxx
- Name=ns2.*their ISP domain*
Type=A, Class=1, TTL=2607 (43 Minutes 27 Seconds), RDLENGTH=4
IP Address=xxx.xxx.xxx.xxx
- Name=ns2.*their ISP domain*
Type=AAAA, Class=1, TTL=1861 (31 Minutes 1 Second), RDLENGTH=16
IPv6 Address=2001:898:2000:12:0:0:0:2
---
They say we are not listed in some blacklist or beeing blocked by their firewall, so i'm at a loss, our exchanger can connect fine to any adress on the net. Even though i believe this is not our problem, im still inclined to look for some solution.
Can anyone find something wrong?

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Marco Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 07 June 2005 Location: Netherlands Status: Offline Points: 137	Post Options Post Reply Quote Marco Report Post Thanks(0) Quote Reply Topic: DNS question Posted: 16 March 2006 at 8:09am
	This isnt really related to SPF, i apoliogise for that. Since this is a forum with mega expertise in the area of mail servers and their setup, i post my question here. One of our customers is giving me a lot of grief since none of our users seem to be able to send them emails. Our mail system cannot connect to their exchanger for some reason (host unavailable error), but when i do an mx-record lookup it seems all allright to me, except maybe their entry for their 2nd nameserver. (i've never seen such entry before, but i'm no expert) mx quesry on their domain: Header: ID=24159, QR=Response, Opcode=QUERY, RCODE=NO ERROR Authoritative Answer=No, Truncation=No Recursion Desired=Yes, Recursion Available=Yes QDCOUNT=1, ANCOUNT=2, NSCOUNT=3, ARCOUNT=4 Question: Name=their domain name, QTYPE=MX, QCLASS=1 Answer Section: - Name=their domain name Type=MX, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=20 Preference=10, Mail Exchange=mxa.mail.their ISP domain - Name=their domain name Type=MX, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=8 Preference=10, Mail Exchange=mxb.mail.their ISP domain Authority Records Section: - Name=their domain name Type=NS, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=16 Name Server=ns2.their ISP domain.net - Name=their domain name Type=NS, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=6 Name Server=ns3.their ISP domain - Name=their domain name Type=NS, Class=1, TTL=15674 (4 Hours 21 Minutes 14 Seconds), RDLENGTH=6 Name Server=ns1.their ISP domain Additional Records Section: - Name=mxa.mail.their ISP domain Type=A, Class=1, TTL=33 (33 Seconds), RDLENGTH=4 IP Address=xxx.xxx.xxx.xxx - Name=mxb.mail.their ISP domain Type=A, Class=1, TTL=18 (18 Seconds), RDLENGTH=4 IP Address=xxx.xxx.xxx.xxx - Name=ns2.their ISP domain Type=A, Class=1, TTL=2607 (43 Minutes 27 Seconds), RDLENGTH=4 IP Address=xxx.xxx.xxx.xxx - Name=ns2.their ISP domain Type=AAAA, Class=1, TTL=1861 (31 Minutes 1 Second), RDLENGTH=16 IPv6 Address=2001:898:2000:12:0:0:0:2 --- They say we are not listed in some blacklist or beeing blocked by their firewall, so i'm at a loss, our exchanger can connect fine to any adress on the net. Even though i believe this is not our problem, im still inclined to look for some solution. Can anyone find something wrong?
	Anyone who is capable of getting himself made president, should on no account be allowed to do the job. D.Adams

Marcus Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 25 July 2005 Location: United States Status: Offline Points: 21	Post Options Post Reply Quote Marcus Report Post Thanks(0) Quote Reply Posted: 16 March 2006 at 10:00am
	How are you running the MX query. If its not from your dns servers your probably going around the problem. Try this: nslookup -q=mx "their domain name" from a machine using your dns server. You should get a response like Server: your_dns_servername Address: your_dns_server_ip Non-authoritative answer: their domain name MX preference = 10, mail exchanger = zzz.their domain name zzz.their domain name internet address = aaa.bbb.ccc.ddd If the nslookup fails try clearing your dns cache. I've seen instances where the cached lookup would be corrupted and clearing the cache would clear up a lookup problem. Marcus

Marco Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 07 June 2005 Location: Netherlands Status: Offline Points: 137	Post Options Post Reply Quote Marco Report Post Thanks(0) Quote Reply Posted: 16 March 2006 at 10:52am
	Im using the tool 'cyberkit' and can enter any DNS server's IP to see how that DNS server 'sees' things. I tried 3 different DNS servers, all give the same result, so i don't think that that is the problem. Apart from that i am not running DNS for our domain, im using the DNS server of our ISP for the lookups (like the mailserver)
	Anyone who is capable of getting himself made president, should on no account be allowed to do the job. D.Adams

LogSat Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 25 January 2005 Location: United States Status: Offline Points: 4105	Post Options Post Reply Quote LogSat Report Post Thanks(0) Quote Reply Posted: 16 March 2006 at 10:59am
	Stupid question. From an MSDOS prompt on your mail server, have you tried: telnet mxa.mail.their ISP domain 25 and telnet mxb.mail.their ISP domain 25 to see if you are getting a connection and a welcome banner from them?
	Roberto Franceschetti LogSat Software Spam Filter ISP

Marco Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 07 June 2005 Location: Netherlands Status: Offline Points: 137	Post Options Post Reply Quote Marco Report Post Thanks(0) Quote Reply Posted: 16 March 2006 at 11:10am
	Not a stupid question :), i tried (from the mailserver) and get this response: 220-mx1.mail.ispdomain ESMTP Exim 4.60 Thu, 16 Mar 2006 17:06:32 +0100 220- Sending spam or unsolicited commercial e-mail to this server is strictly 220- prohibited by our NO UBE / NO UCE policy. Abuse will be prosecuted and/or 220 charged per attempted recipient at international postal rates. So it seems our mailserver DOES see this host, it's getting weirder and weirder
	Anyone who is capable of getting himself made president, should on no account be allowed to do the job. D.Adams

LogSat Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 25 January 2005 Location: United States Status: Offline Points: 4105	Post Options Post Reply Quote LogSat Report Post Thanks(0) Quote Reply Posted: 16 March 2006 at 11:59am
	Well, at this point then try actually sending an email using telnet so you can see the whole conversation: telnet mxa.mail.their ISP domain 25 220 mail2.netwide.net Welcome to SpamFilterISP SMTP Server v2.7.1.537 HELO mail.mydomain.com 250 HELO mail.mydomain.com MAIL FROM:<logsat@netwide.net> 250 Address Okay RCPT TO:<test@logsat.com> 250 test@logsat.com Address Okay DATA 354 Start mail input; end with <CRLF>.<CRLF> From: logsat@netwide.net To: test@logsat.com Subject: test test email . 250 OK In the telnet session above, what you type is red, the server's answer is blue. Don't forget about the standalone final "dot" on the last line. If you see anything other than a 250 numeric code at the end, there will be a problem delivering the email, and the server should tell you what the reason is.
	Roberto Franceschetti LogSat Software Spam Filter ISP

Marco Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 07 June 2005 Location: Netherlands Status: Offline Points: 137	Post Options Post Reply Quote Marco Report Post Thanks(0) Quote Reply Posted: 17 March 2006 at 3:36am
	hmm, i sent them a testmail using telnet and everything went as you said Roberto, gonna give the old-fashioned telephone a try now :) Thanks a lot for the help, i now know for sure its not our problem.
	Anyone who is capable of getting himself made president, should on no account be allowed to do the job. D.Adams

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