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SMTP error 501

Discussion in 'E-mail Discussions' started by Andysweb, Jan 24, 2011.

  1. Andysweb

    Andysweb Member

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    I have had an email bounce back saying that;


    SMTP error from remote mail server after initial connection:

    IP Address <xx.xx.xx.93> - HELO/EHLO Invalid or Non-Existent Reverse DNS

    but my account for this domain has the server as xx.xx.xx.97

    Your advice is appreciated.

    Thank you

    Andy
     
  2. LinuxTechie

    LinuxTechie Well-Known Member

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    Hi Andy,

    Can you please check whether the domain's IP is having Reverse dns or not. I hopes the domain's MX is also pointing to the same server. ( O/w you need to check Rdns of the remote server to which MX is pointed.) You can use the below given URL to check whether the IP has got Reverse DNS or not.

    Ip Tools, DNS tools, internet tools, WHOIS, traceroute, ping, domain name tools >> Reverse DNS Lookup

    If Reverse Dns is not set for the IP you need to contact your host regarding this.
     
  3. Andysweb

    Andysweb Member

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    Hi,

    Thank you for the reply. I am running a dedicated server.

    I have added the Rdns record (there was not any) and the MX records are pointing to the domain name.

    Do you think I have to wait for this change to propergate?

    That tool is still showing that there is no reverse dns.

    Thank you
     
  4. LinuxTechie

    LinuxTechie Well-Known Member

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    Hi Andy,

    You are welcome. It may not take long for propagation and the results in the iptools may be a cached one. This can be checked using the below given commands :

    If you are confused of the results paste the output here and I will verify it for you.
     
  5. Andysweb

    Andysweb Member

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    Hi,

    Thank you again for your support. can you advice me where to run the commands? Is it in the shell via root?
     
  6. LinuxTechie

    LinuxTechie Well-Known Member

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    Hi Andy,

    Please take a terminal and run it from your local machine.

    O/w you can simply use another tool which is mentioned below.

    Also check whether you are able to send mails now.
     
  7. Andysweb

    Andysweb Member

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    I have just tried to resent the email but I am still getting the same message. :( May be it is cached.
     
  8. Andysweb

    Andysweb Member

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    Silly question to I set up the reverse DNS entry in the existing domain record or a new one?
     
  9. LinuxTechie

    LinuxTechie Well-Known Member

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    Hi Andy,

    Let me know the domain so that I can check whether it is set correct or not. If you are not sure to set you need to contact your host or DC techs for this.
     
  10. Andysweb

    Andysweb Member

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    the domain is totallyexpat.com

    Thank you
     
  11. Andysweb

    Andysweb Member

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    PS I think my isp is very slow in updating DNS..
     
  12. LinuxTechie

    LinuxTechie Well-Known Member

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    Hi Andy,

    I could see that Rdns is not set for the IP. If you are sure you have set it correctly then we can wait for it to propagate. O/w please contact your host or DC to do it for you.
     
  13. Andysweb

    Andysweb Member

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    Hi,

    my host are going to do this for me.
    Should I delete the record I have set up in Cpanel?

    I think I will wait for them to fix that and see what happens before deleting that record.

    Your help was very much appreciated.

    Thank you
     
  14. LinuxTechie

    LinuxTechie Well-Known Member

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    Hi Andy,

    Thanks for posting what you have done. Unfortunately what you have done is wrong. It is not possible to set Rdns from cpanel. You can delete the record you have made.

    It is good to hear that you contacted your host. I am sure they will sort it out soon. Good luck.
     
  15. Andysweb

    Andysweb Member

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    I meant under WHM .. shall i delete the record.
     
  16. LinuxTechie

    LinuxTechie Well-Known Member

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    Hi Andy,

    I thinks you better update your host what you have modified than deleting it. If you are sure of reverting it back as before you can do it from your end.
     
  17. cPanelTristan

    cPanelTristan Quality Assurance Analyst
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    Hello,

    If you do not control the IP delegation, and most servers do not have control of the IP as the IP provider does, then you cannot setup a PTR record for rDNS in WHM and have it work. If you did set this up in WHM, then you should remove the PTR record you'd setup and let your host do it if they have the IP delegation.

    There is a major difference between IP zone records and domain DNS zone records. An IP zone record for PTR for rDNS is setup this way:

    Configuring Reverse DNS in WHM

    The only way these zones can be setup and work will be when the IP provider delegates control of the IP to the server, which again is rare and only happens if your IP provider does confirm they've delegated the control to your machine.

    Thanks.
     
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