My order is: IP Whitelist Email / Domain Whitelist (incl. Auto Whitelist) Custom Blacklist Directory Harvesting Sender Policy Framework Keyword Whitelist DNS Blacklists Spam URI Realtime Blocklists Bayesian Analysis Header Checking Keyword Checking ________________________________ From: Jason Davis [mailto:JDavis@xxxxxxxxxx] Sent: Thursday, October 13, 2005 3:33 PM To: [ExchangeList] Subject: [exchangelist] RE: GFI Mail Essentials 11 - NDR's and SMTP Ma il Queue http://www.MSExchange.org/ Chris, Thanks again for all your time and knowledge. Incidentally, how have you configured your priorities in GFI? Right now, I have Whitelist at the top, but I will change to Directory Harvesting per your last email. --Jason ________________________________ From: Chris Wall [mailto:Chris.Wall@xxxxxxxxxxxxxxxxxxx] Sent: Thursday, October 13, 2005 12:16 PM To: [ExchangeList] Subject: [exchangelist] RE: GFI Mail Essentials 11 - NDR's and SMTP Mail Queue http://www.MSExchange.org/ 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