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Delivery Status Notifications -- get rid of "success"

I need some help with DSN.

I have been using sendmail since 1995.  I have an Ubuntu 12.04 server 
which my best information is, uses sendmail 8.14.4.  I am having a 
problem that mail is coming in from an address with a delivery status 
notification request. Sendmail is delivering the email either locally or 
following a .forward addresses and delivering successfully. Then sendmail 
is generating a successful delivery status notification back to the 
apparent sender of the original message and that outgoing message is 
failing.  I have set (please excuse that I am walking from one computer 
to another retyping and may not have it character perfect here):

define('conf_PRIVACY_FLAGS','......,noreceipts')dnl  in the sendmail.mc

and have verified that leads to 

O PrivacyOptions=.....,noreceipts  in sendmail.cf 

and I have done sudo reloads, and rebooted the server at least twice, is 
should be working with the new sendmail.cf file.  I have googled, and 
found scant information on DSN, only a recommendation to insert 
"noreceipts", and another recommendation to not do that, that that is too 
strict and will cause problems.  

If I can, I would like to continue to allow DSN in the case of delivery 
failures because those alert senders I did not get their mail properly, 
but I can live without those to solve this problem.

What I am concerned is happening is one of two things: 

Either a DDOS attacker is using a spam route to succeed:  He has found a 
way to send emails from the target domain to my server, so as to pass 
regular checks on forged mail, and my server is delivering the spam 
locally -- it is spam, I checked -- and then in repeatedly trying to 
provide the requested success notification, my server is participating in 
delivering a DDOS attack on the originating domain, using my server's 
cron 
attempts to resend the notification frequently.  My logs are full of 
these attempts.   

Or... a botnet has indeed compromised something in my network (as CBL 
reports) and this has landed my server on a refuse list used by the 
sending domains, and that is why the success notifications for spam are 
not being delivered...  But the spam keeps coming apparently from these 
domains, and keeps requesting DSN.  

But both of these beg the question, why is sendmail ignoring "noreceipts" 
and continuing to try to send these notifications after I edited .mc, 
compiled to .cf, and performed reloads and reboots and manually flushing 
the mqueue repeatedly?   

How exactly do I prevent sendmail from generating success notifications?

Thank you 

Matt
m_j_malone@hotmail.com
0
Matt
11/22/2016 12:38:55 AM
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Matt  wrote:

> to another retyping and may not have it character perfect here):

> O PrivacyOptions=.....,noreceipts  in sendmail.cf 

> should be working with the new sendmail.cf file.  I have googled, and 

Provided sendmail isn't using some other .cf file...

telnet localhost 25
....
EHLO example.com
....
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-8BITMIME
250-SIZE 19000000
250-STARTTLS
250-DELIVERBY
250 HELP


Is DSN in the list on your system?


Did you set this option by accident?
# Return-Receipt-To: header implies DSN request
#O RrtImpliesDsn=False

> attempts to resend the notification frequently.  My logs are full of 
> these attempts.   

Please post at least one of those (all of the log entries for one mail
including the DSN).


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0
Claus
11/22/2016 12:18:46 PM
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