Reverse DNS Lookup

cmedik

• August 01, 2014 04:22

In WHM I use a script called mail scanner, which lets me look at incoming and outgoing mail on the server. Problem I am seeing is that I get spammed and when I got to look into the message the hostname always says Reverse lookup failed and there mail still comes through. Is there a setting in WHM somewhere that I can set up or have to turn on and says if reverse lookup failed it will deny the message and or email? Thanks for time.

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  cPanelMichael

  • August 01, 2014 13:33

  Hello :) You may find the following document useful from Exim: [url=http://www.exim.org/exim-html-current/doc/html/spec_html/ch-access_control_lists.html]42. Access control lists In particular, you should search for this term: verify = reverse_host_lookup [QUOTE] This condition ensures that a verified host name has been looked up from the IP address of the client host. (This may have happened already if the host name was needed for checking a host list, or if the host matched host_lookup.) Verification ensures that the host name obtained from a reverse DNS lookup, or one of its aliases, does, when it is itself looked up in the DNS, yield the original IP address. If this condition is used for a locally generated message (that is, when there is no client host involved), it always succeeds.
  Thank you.

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  cmedik

  • August 01, 2014 16:48

  Ok it is a good doc. Since I am new to WHM where would I go to set this. Any help appreciated?

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  cPanelMichael

  • August 01, 2014 17:04

  In previous threads, advice has been to browse to: "WHM Home " Service Configuration " Exim Configuration Manager " Advanced Editor" Search for "custom_begin_check_message_pre" and try adding the following entry to that field: require verify = reverse_host_lookup Let us know if that's helpful. Thank you.

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