David Booth
Goulburn Internet
+61 2 48 229131
On 06/12/2009, at 12:04 PM, Gerald Waugh wrote:
>
> On Sat, 2009-12-05 at 14:02 -0800, Andrew Danneffel wrote:
>> Hi there,
>>
>> My Blue Quartz server is constantly being hammered with email to users
>> that do not exist on the server (I believe they are referred to NDRs).
>> The maillog lists thousands and thousands of these "No such user here"
>> errors each day. Strangely the vast majority of them are to two
>> domains, each which start with "a". I don't believe the server is
>> automatically sending out responses to these senders as this has been
>> happening for some time and the server is not blacklisted from what I
>> can see. I understand that these messages are from spammers and that
>> the sender email addresses are spoofed.
>>
>> I am wondering what (if anything) can be done to prevent the server
>> from processing and logging all of these useless messages. I suspect
>> all of these mail requests are generating significant data transfer.
>> Is it simply a fact of life or can some component of the mail system
>> be optimized to stop it?
>>
>
> Are you using any catchall email accounts?
> If so stop using them!
>
> Is you sendmail.mc / cf configured to accept unresolvable domains?
> If so reconfigure
> Also check if Sendmail configured for DNS-Based Blacklisting
>
> Gerald
> The problem with these NDRs is that they are from valid domains. They
> are bounces directed to the sender of a 'joe' email which looked like
> it came from my/Andrew's host. If I configure my client with
> gwaugh (at mark) raqware.com as the email address and send to
> abcwxyz (at mark) hotmail.com you will get the 'no such user' bounce from
> hotmail. They are valid NDRs and need to be handled by my/Andrew's
> host.
If I post a letter to an unknown address with your address on the back
then the post office will return it to you. Or if I put a non-existent
address on the back they will still try and send it there.