Any good free DNS checkers?

[Durbs]

Does anyone know an equivalent to http://www.dnsstuff.com/ where you dont need to supply credit card details to use it?

Need to resolve an issue with a clients domain name, mainly the fact their mail is getting actively refused in various places. They use my mail server to relay which i've checked and is not blacklisted itself (their MX also points to and resolves to my server). All the free DNS and MX checkers i've used show no issues with the domain but if i try http://www.dnsstuff.com/ it shows 2 issues but wont tell me what they are till i pay!

The dnsstuff website does actually look good but i don't do enough of that sort of stuff to warrant a subscription and dont like handing over CC details for 'free trials'.

Ta.

[blacjac]

Sounds likely to be a reverse DNS lookup issue.

When some mailservers recieve mail, they will do a reverse DNS lookup on the IP address, if it doesn't match what the sending mailserver says it's called, they will reject the message.

try www.dnstools.com

[pmeswani]

www.demon.net/external.

[Durbs]

Ta. Looking at the domain, 'mail.theclient.com' and 'www.theclient.com' point to my own server. But just 'theclient.com' on its own points to a different IP at her domain name registrar.

Wonder if thats the issue?

[blacjac]

what happens if you do a reverse lookup on mail.theclient.com?

If it resolves to something other than the mail server's IP address (may resovle backwards) then that's your problem.

[Durbs]

what happens if you do a reverse lookup on mail.theclient.com?

If it resolves to something other than the mail server's IP address (may resovle backwards) then that's your problem.

Just tried running mail.theclient.com through http://www.mxtoolbox.com/diagnostic.aspx and it passes all tests including reverse DNS (although it says OK - 67.199.xxx.xxx resolves to mail.DurbsCo.co.uk i.e my own ltd, different name but right IP which i assume is all that matters?).

[blacjac]

Just tried running mail.theclient.com through http://www.mxtoolbox.com/diagnostic.aspx and it passes all tests including reverse DNS (although it says OK - 67.199.xxx.xxx resolves to mail.DurbsCo.co.uk i.e my own ltd, different name but right IP which i assume is all that matters?).

That will be the problem.

The client mail server is sending out mail and stamping it as being from 67.199.xxx.xxx, mail.clientco.com

When the mail is received the receiving mail server checks this out using reverse DNS, and this is telling it that 67.199.xxx.xxx isn't "mail.clientco.com", it's actualy mail.durbsco.co.uk.
This makes the receiving mailserver suspect that the email might be spam as it is telling you it is coming from one place, but reverse DNS is telling you it is coming from somewhere different.

Some mailservers will let it through, some will reject it, it depends on the security setting of the mail server.

You need to find out who is responsible for the DNS of both DurbsCo and ClientCo and get the reverse entry removed from DurbsCo's DNS server and added to the reverse zone of CLientCo.

[Spoiler]

When the mail is received the receiving mail server checks this out using reverse DNS, and this is telling it that 67.199.xxx.xxx isn't "mail.clientco.com", it's actualy mail.durbsco.co.uk.
This makes the receiving mailserver suspect that the email might be spam as it is telling you it is coming from one place, but reverse DNS is telling you it is coming from somewhere different.

Some mailservers will let it through, some will reject it, it depends on the security setting of the mail server.

I was also under the impression that the name in the PTR record had to match the name in the MX record, but speaking to a DNS\server chap last week, he reckons it's a myth and as long as a PTR exists, it doesn't matter if the names match or not - he hadn't come across a mail server that cares about this.

So, I'd be interested if this is your problem, or if it's something else!

[blacjac]

I was also under the impression that the name in the PTR record had to match the name in the MX record, but speaking to a DNS\server chap last week, he reckons it's a myth and as long as a PTR exists, it doesn't matter if the names match or not - he hadn't come across a mail server that cares about this.

So, I'd be interested if this is your problem, or if it's something else!

I have come across this exact issue this year already.

I set up a new Ltd co & domain, but emails to my network provider and accountant were getting bounced.

It was because my mail server (mail.myco.co.uk) had been put into the reverse DNS zone as mailsrv.myco.co.uk.

I suspect you may be right about MX records though, as my MX records are all set up with IP addresses and not host names.

[Ardesco]

I was also under the impression that the name in the PTR record had to match the name in the MX record, but speaking to a DNS\server chap last week, he reckons it's a myth and as long as a PTR exists, it doesn't matter if the names match or not - he hadn't come across a mail server that cares about this.

So, I'd be interested if this is your problem, or if it's something else!

Try sending something to an AOL e-mail address, they probably have the most anal reverse IP checking system on the net.