550-Sorry, we require a valid and consistent reverse DNS

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phil54
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550-Sorry, we require a valid and consistent reverse DNS

Post by phil54 » 2008-02-07 12:39

550-Sorry, we require a valid and consistent reverse DNS before we can accept, i'm getting this error message from one domain (major isp).

anyone got any ideas? i need to get this sorted asap.

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Post by ^DooM^ » 2008-02-07 14:47

Fix your RDNS of your IP. It should match the domain you are sending on or at least a FQDN (top level).

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Post by phil54 » 2008-02-07 15:45

Thanks doom, i think i have. I've created a ptr record of the ip and then the domain.

Do you think thats right?

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Post by ^DooM^ » 2008-02-07 16:25

Depends if you control your DNS or not. Usually you will need to contact your hosting provider or ISP and have them change it.

Open up a command prompt

type nslookup

put your IP address in there hit return and see what the result is.

phil54
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Post by phil54 » 2008-02-07 16:44

We control the dns for each domain, but not the top level dns.

Dont get much back from nslookup when i'm on the server

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Post by ^DooM^ » 2008-02-07 17:01

PM me your domain name please and I will check for you.

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Post by phil54 » 2008-02-07 17:13

Sent :D

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Post by ^DooM^ » 2008-02-07 17:49

Didn't receive a PM mate

phil54
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Post by phil54 » 2008-02-07 17:51

hmm tried a couple of times, that's a bit weird.

How were you going to check?

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Post by phil54 » 2008-02-07 18:54

After reading a couple of articles around the web, i'm definately missing a valid ptr record for the domain in question.

How have you all got your ptr set?

Example:

Domain: me.com

a record: me.com
mx record: mail.me.com
ptr: me.com points to mail.me.com

Would that be valid?

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Post by phil54 » 2008-02-07 19:29

or could someone post a domain, that has a valid ptr record so i can check it up on this site please?

http://www.kloth.net/services/nslookup.php

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Post by ^DooM^ » 2008-02-07 21:09

goto that website from your hmailserver machine

near the bottom of the page it will say the following

You are coming from IP address 123.123.123.123 using port 2529.
A DNS reverse lookup shows your hostname as mydomain.com.

Is the domain correct?

If it isn't you need to setup a PTR record to mydomain.com not mail.mydomain.com

If it doesn't change you need to contact either your ISP or Hosting provider (Whoever gave you your IP address and ask them to change it).

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Post by danny6167 » 2008-02-07 21:11

Can you have more than 1 RDNS record. For more domains?

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Post by ^DooM^ » 2008-02-07 21:14

No you can only have 1 RDNS record per IP.

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Post by jimcdonald » 2008-02-08 00:02

Which is a problem if you have more than one domain per IP.

IP's are quite hard to come by and you need to justify them nowadays, usually needing a reason such as SSL as to why you need more IP's for domains.

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Post by SorenR » 2008-02-08 00:50

jimcdonald wrote:Which is a problem if you have more than one domain per IP.

IP's are quite hard to come by and you need to justify them nowadays, usually needing a reason such as SSL as to why you need more IP's for domains.
Not really, you can have MX records for different domains all using the same mail server. It's the PTR of that specific mail server that need to match the EHLO/HELO host name of the mail server.
Remember that when one server connects to another it only knows about the IP address. the EHLO/HELO host name can be faked but if it matches the IP address it is very likely that it is valid.
This is one of the reasons why home DSL users, having their own mail server, need to use the ISP SMTP server for outbound relaying. Their own RDNS belongs to the ISP.
Am I making sense or just babbling away?

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Post by ^DooM^ » 2008-02-08 04:11

That is exactly right. What a lot of companies do is have a generic hostname that they use for all email for all domains. As long as the IP matches the EHLO/HELO domain usually it will pass without issue.

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Post by phil54 » 2008-02-08 11:31

Would the ptr record need to match the Host name in the smtp settings in hmailserver?

Edit:

I've just checked this aol site, for checking reverse dns:

http://postmaster.aol.com/tools/rdns.html

The results show the ip address and then the hosting company's name. It's saying it's correct and we do have reverse dns.

My problem is this, if the domain company is called Hosting.co.uk and the domain in question is mydomain.com. We can obviously setup the dns for each domain, how can we get the ptr record to match the hosting company name?

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Post by ^DooM^ » 2008-02-08 15:16

You will need to ask the hosting company to change it.

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Post by phil54 » 2008-02-08 15:26

Good news, it's now working :D Thanks for the help in this thread guys.

In the end, i created a ptr record to match the MX Record and the mail has been acceepted by the isp :)

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