[CentOS] Postfix - message queue filling with Host or name not found - try again

Rob Kampen rkampen at kampensonline.com
Sun Nov 21 22:47:02 EST 2010


Ben McGinnes wrote:
> On 17/11/10 7:26 AM, Rob Kampen wrote:
>   
>>>> Examining the postfix queue with postqueue -p:  I see many
>>>> (Host or domain name not found. Name service error for
>>>> name=bdgiedjhea.po6e4ina.com type=MX: Host not found, try again)
>>>>                                          Jake at bdgiedjhea.po6e4ina.com
>>>> My question - why does this stay in the message queue - why not dumped
>>>> back with message undeliverable or dropped?
>>>>         
>
> What is the complete output of postqueue -p?  What is the From address
> and, more to the point, is it MAILER-DAEMON?
>   
Yes it is
>   
>> Agreed, however this opens a potential DoS attack vector - I'm
>> trying to determine why my postfix even has these requests present
>> as I'm not initiating the emails (as far as I know) and I do not
>> forward emails for any other domains.
>> I feel like I'm missing something......confused maybe
>>     
>
> It could be backscatter.
>
> Run postqueue -p and pick one of the messages, it shouldn't matter
> which.  Then run:
>
> postcat -q $MSGID | less
>
> Where $MSGID is one of the messages in the queue.  That will show you
> the message and headers.  I'd be willing to bet it's your server
> trying to send a rejection/spam detection to a server.
>
>   
Correct - thanks for the pointers on how to track it down - so now my 
question is how do I set things up to simply try this once and then drop 
it, rather than queue it up for the next five days with all the 
attendant dns errors. This is definitely at the boundaries of my mail 
setup experience - for some reason the other two mail servers I run do 
not seem to get the same level of spam and thus I seldom notice this.
> Regards,
> Ben
>
>   
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