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Sender IP must resolve

Discussion in 'E-mail Discussion' started by ramorse, Jan 24, 2018.

  1. ramorse

    ramorse Well-Known Member

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    I have a new server and I moved my own domain to it. Everything works fine, but when I send email to one address, and I know that address is on a Windows server, it bounces back with the message: Sender IP must resolve.

    Of course the IP of the server resolves to my server's name, not the domain name I am sending from. Not sure how to "resolve" this.
     
  2. webhostuk

    webhostuk Well-Known Member

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    Twitter:
    It can be due to incorrect mail server setup or DNS resolving issue, as suggested can you check if the mail server is pinging to correct IP.
     
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  3. keat63

    keat63 Well-Known Member

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    Could this be related to RDNS.
    I seem to recall something similar when I configured my server and me having to ask my data centre to configure this at thier end.
     
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  4. ramorse

    ramorse Well-Known Member

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    When I ping the remote domain from this server I have not problem. I will check with the DC about rDNS. That does sound familiar to me, too.
     
  5. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    Check to ensure the cPanel server's IP address and the IP address you are sending the email from (it also appears in the email headers) have RDNS records configured. You can test this via SSH by running the "host $IP" command.

    Thank you.
     
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  6. ramorse

    ramorse Well-Known Member

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    Running that command I just get Usage: host with a list of helper commands.

    I get the same result running that command on 2 other servers.
     
    #6 ramorse, Jan 25, 2018
    Last edited by a moderator: Jan 25, 2018
  7. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    You have to replace "$IP" with the actual IP address of your server, and your home IP address (from the computer you are using to send out the email).

    Thank you.
     
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  8. ramorse

    ramorse Well-Known Member

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    Oh. Duh. Feeling dumb. Doing that, I get a return like some.ip.add.in-addr.arpa. not found: 3(NXDOMAIN)

    I run the same command on another server and get the same not found result.
     
  9. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    That suggests a RDNS entry does not exist for the IP address you checked. For the cPanel server's IP address, you can contact your data center or hosting provider to have them update the RDNS entry for the server's IP address to point to the server's hostname.

    Thank you.
     
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  10. ramorse

    ramorse Well-Known Member

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    I get the same kind of result when I run it from within the shell of my local computer from which I am trying to send the message, using its IP.
     
  11. ramorse

    ramorse Well-Known Member

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    I have already contacted the Data Center about this. Waiting for a response.
     
  12. ramorse

    ramorse Well-Known Member

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    I do find it strange that running the command on 2 other servers, both of which previously hosted my domain I get the same result, yet I have not seen a bounce like that from any domain when my domain was on the other servers.
     
  13. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    Are you sure the other servers that hosted your domain name also didn't have a RDNS record setup for the IP address used to send email? For instance, are you checking the same IP address on every server with that command, or the IP address that would have been used to send email were your domain name still hosted on that server?

    Thank you.
     
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  14. ramorse

    ramorse Well-Known Member

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    All I can tell you is that I ran the command host $IPoftheserver from within each of the old servers and got the same result as the new server(except the IP address at the front was different, of course):
    Host ipaddress.in-addr.arpa. not found: 3(NXDOMAIN)
     
  15. cPanelMichael

    cPanelMichael Forums Analyst
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    Hello,

    The other factor to consider is that some remote mail servers will check to see if RDNS is enabled for the IP address of the actual email sender (most email clients include the IP address of the sender in addition to the IP address of the server).

    Thank you.
     
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  16. ramorse

    ramorse Well-Known Member

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    Maybe. But that would be pretty counterproductive since unless you have a dedicated IP, the IP handed off to you by your ISP can change if, say your power goes out and your router gets rebooted. And unless the ISP has set this up for every IP, your email could work one day and then not work the next.

    I got a similar bounce (although it said it was delayed 48 hours, but the reason was the same) sending to a client I have been emailing for years with that same domain, and for a very long time with the local IP from my ISP. And I only got that bounce notice after I moved to the new server. Now I'm concerned that clients I move to the server will start running in to the same issue. I can work around it by using my gmail.com account if I have to. But that's not an adequate solution for clients.
     
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