RE: GFI Mail Essentials 11 - NDR's and SMTP Mail Queue

  • From: "Chris Wall" <Chris.Wall@xxxxxxxxxxxxxxxxxxx>
  • To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
  • Date: Thu, 13 Oct 2005 15:15:43 -0400

Jason,

 

   Most spam is from 'Spoofed' e-mail accounts, therefore when an NDR is
sent to the Spoofed e-mail account (and of course they will fail due to
the fake address) it is retried for delivery based upon your SMTP
settings.  

 

    By default, I believe that mail is retried for 48 hours before being
deleted.  Here is what I have done to ease the issue:

 

1.      Use the 'Directory Harvest' feature of GFI

        a.      This verifies that an e-mail address exists in your
domain via an LDAP lookup before GFI will continue processing the mail
for delivery and additional spam checks.  You want to make sure this is
the first check that is done before all other Spam filters (you can
prioritize GFI checks in version 11)
        b.      If any mail triggers the 'Directory Harvest' check,
configure this to NOT send and NDR.

                                                               i.
The only downfall here is if someone sends a legitimate e-mail and
mistypes one of your user's e-mail addresses, they will not be notified
that the mail was not delivered.  This has not been an issue for me yet.

                                                             ii.
The Directory Harvest feature is so efficient for our organization that
very few e-mails (in comparison) trigger the other SPAM checks.

2.      Turn off NDR's for the SPF, Blacklist and DNS Blacklist options.
(if you have them enabled)

        a.      99% of the e-mails that trigger these filters are known
spammers.  Who cares if they get an NDR.

3.      Turn on NDR's for the Bayesian, Key Word and Header Checking
options
4.      Set up and Automated task to delete your Badmail directory on a
nightly, or weekly basis.
5.      You can also play around with the default settings for 'Retry
Mail Delivery' so that they are not retried for 48 hours.  I have
adjusted mine to try for only 24 hours before failing the message.  

 

This should help minimize the amount of mail that builds up in your
queues and still notify the senders when they are being filtered out...

 

Regards,
Chris

 

________________________________

From: Jason Davis [mailto:JDavis@xxxxxxxxxx] 
Sent: Thursday, October 13, 2005 2:57 PM
To: [ExchangeList]
Subject: [exchangelist] GFI Mail Essentials 11 - NDR's and SMTP Mail
Queue

 

http://www.MSExchange.org/

Hello all, 
I thought I'd send you a quick note regarding my findings today: 
This issue may have been a "no-brainer" for you guys, but I rebuilt my
original GFI server yesterday (Mail Essentials 11) and tested the SMTP
gateway for a few hours to keep an eye on the queues - no problems.
Then, I installed the latest build version for Mail Essentials 11. When
I got home, I decided to check the GFI server remotely to see how the
queues were doing. I found a lot of emails piling up in the queues as
well as 1000's of emails piling up in the Badmail folder! Yikes!!! After
scratching my head for a few hours and doing some research online, I
proceeded to disable a feature which I had implemented in the GFI
software for each SPAM filter. The feature involved sending back a NDR
for each SPAM filter (under the "Other" tab - "Generate Non Delivery
Report <NDR>). Each SPAM filter (i.e. SPF, Bayesian, etc, etc.) had that
option checked! Once I unchecked that option for each filter, I had to
delete the mail in the Badmail folder and purge the SMTP mail queue.
Well, I've been running GFI since that change and my queue is purging
fine and there have been NO emails in the Badmail folder. Alas, I think
that that was causing my problem this past weekend! 

Does that make sense to you guys? I'm sure it's a lack of knowledge on
my part, but I didn't realize that generating NDR's would cause my mail
queue to get "backed-up" as well as creating thousands of emails in my
Badmail folder. I could see how this would bring the GFI server to its
knees after a while. Does anyone have that option checked to "Generate
Non Delivery Reports"?? If so, how are your servers handling it? I'd be
very curious...... 

It seems to me that GFI would not put that option in its software, if it
was going to cause such a problem? Hmmmm......... 

Thanks for any comments, in advance! 
--Jason Davis 

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