Shared IP address - Domains not able to reply to Craigslist because of rDNS

Is there a solution to this problem?

My main server domain passes rDNS without issues when trying to reply to a craigslist ad. If one of my clients who are on a separate (shared) IP address try it it immediately bounces.

Connected to but greeting failed.
Remote host said: 554 [<----fictitious IP obviosuly] Please setup matching DNS and rDNS records:

The IP address for their domains ( resolves back to my domain that is located at ( instead of their own.

Craigslist appears to be the only service this is a problem with but I may lose at least one customer unless I can get this resolved.


Hi machten

I’m sorry, your not giving details to help in resolving your issue

You can pm me both your main IP address and the shared IP address which failed, so I can test

I have a feeling there is no rdns on the second IP address

Please remember, unless you have been delegated full control over your cidr or ip addresses, you cannot assign rdns/ptr records

There is 1 more thing it could be, do you use IPv6 at all

Many thanks


Hey John,
No IPv6 on this server. I believe that my server PTR is handled by the data center it resides in because I had them add mine (I think but it’s been like 14 years!)

I contacted them last night about adding additional IPs and domains to their delegation and am waiting to hear back from them as I type this - its been like 12 hours already.

Can we have multiple domains doing reverse DNS back to a single IP address if this is indeed the issue?

Hi machten

Many thanks

Datacentres usually provision within the hour for ptr/rdns

Yes, it is possible but highlight unusual for this to happen

All you need is a ptr/rdns for your IP address and make sure you have a corresponding A record matching the ptr/rdns record e.g. Rdns = and A record (which matches your server or shared IP address)

If it becomes an issue due to time for rdns, you could set all email to be sent from your server IP address, and not any other IP address

I hope that helps a little

Many thanks


How can I get the email to send from my IP address? That would be an ideal situation for now…Then I can deal with the data center later.

I sent you a couple of PMs…I am not sure they all went through though…

Hi Machten

Many thanks, and replied to your PM
Firstly though, please delete your PTR shown in your picture you PM’d me, you do not control PTR so it is not needed in IW DNS

Also, you have a PTR/Rdns on both IP but only 1 A record
To overcome quickly, setup an A record in m** for IP ending 166, my PM to you should make more sense as I have ommited full domain and IP details here. However, this is not 100% as you will be serving 2 IP for domain, so you maybe better to change the mail sender IP in qmail as follows
SSH into server
as root or sudo vi /var/qmail/control/senderip

change all IP to IP ending 164
service smtp restart
check email now been accepted with no bounce back

I hope that helps

Many thanks

Thank you. I edited the IP address in the senderip file. I think that will work for now. I just tried it and no bounce! Your a life saver.

Im concerned about changing the PTR on my DNS. Could this take down the internet connection at the server? Its a long drive to the data center. :frowning:

Thanks again for all your help!

There really is no downside from sending on the same IP as me I guess except for possible spamming issues but I know most of my customers and I wouldn’t expect them to do it intentionally.

Hi machten

Ahh the drive to datacentre haha know it well here in uk for me, over 200 miles away

As long as you only delete the PTR record it should not bring anything down, as your PTR is been served by your datacentre and not your systems. Check the test in my first pm to you, the records do not match your PTR

Sending email from IP address for all is fine, no issues and usually you have a second IP address in readiness, presetup with PTR/Rdns (do as I advice, and set this with different record name), so if your main sending IP address is blacklisted, it takes seconds to change to clean secondary sending IP address and all is good whilst you clean the main sending IP address, then change them back when your happy

Many thanks