[CentOS] DKIM

mouss mouss at netoyen.net
Wed Sep 24 21:53:33 UTC 2008


Andrew Norris wrote:
> John Kordash wrote:
>>> mail.bobhoffman.com != bobhoffman.com
>>
>> Careful here.  Email senders have nothing to do with MX records.  
>> Email receivers do.
>>
>> I believe bobhoffman.com is the email sender in this case.
>>
>> I would doubt this is an issue.  Any split in/out mail server is going 
>> to have a different host for receipt (MX) than send.
>>
>> -John
> 
> You're right, I was making an assumption I shouldn't have.  Namely that 
> there was a single host/ip for both sending and receiving email.  Going 
> back to the logs he posted I'd say that assumption was correct in the end.
> 
>  From the yahoo headers:
> "Received:   from 72.35.68.59 (EHLO mail.bobhoffman.com)"
> 
> So his MTA is EHLOing as mail.bobhoffman.com
> mail.bobhoffman.com resolves to 72.35.68.59 (matches the incoming ip)
> 72.35.68.59 reverses to bobhoffman.com (which doesn't match the host)
> 
> As far as I can tell this will hurt his score.

no, it won't.
- his IP is 72.35.68.59. This resolves to bobhoffman.com, which resolves 
back to the IP. all good.

- his helo is mail.bobhoffman.com, which resolves to 72.35.68.59, which 
is the server that sends mail. that's more than perfect.

- his helo starts with "mail.". He gets a bonus in some places.


> Or am I missing something?

"double lookup" is IP -> name -> IP. you don't do name -> IP -> name.


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