Thanks for your reply, Scott! We already use the SMTP 'Control Access' feature to block IP addresses, and it works fine when our IMail server is connected directly to the offending server (topmost 'Received:' line in the header).
We are using another company's e-mail server as a backup, and when they forward (relay) messages to our IMail server, their IP address becomes the topmost line in the header (the offending server becoming the second line in the header), and 'Control Access' no longer works (ie. only appears to work on the topmost line in the header). The other company does not provide any antispam measures on our messages. To fix this, I thought I would take all the IP addresses we have in the 'Control Access' list and convert them to rules for headers such that they filter on the same IP addresses that are located elsewhere in the message header (ie. IP addresses not in the topmost line of the header). Hence, the reason for my query on blocking CIDR and class C address space. Best regards, Kim ---------- Original Message ---------------------------------- From: "R. Scott Perry" <[EMAIL PROTECTED]> Reply-To: [EMAIL PROTECTED] Date: Thu, 18 Dec 2003 15:00:05 -0500 > >>Can anyone recommend a rule format that will block partial CIDR blocks >>located on irregular IP address boundaries rather than having to list a >>unique rule for each class C address space within that CIDR block? >> >>Also, we block class C address space using the following rule format: >> >> H~iii\.jjj\.kkk\.:NUL >> >>were iii, jjj, and kkk range from 0 to 255. Is there a another/better way >>to do this? > >The best way is probably to use the IMail SMTP "Control Access" file, which >lets you block on CIDR ranges (using netmasks, though -- you can use the >CIDR tool at http://www.DNSstuff.com to convert CIDR ranges and >netmasks). That way, the E-mail never even reaches your server (reducing >bandwidth), and it is 100% accurate (the header filtering isn't). > >Also, if you have Declude JunkMail, you can use CIDR ranges in IP >blacklists (such as 192.0.2.128/23). > > -Scott >--- >Declude JunkMail: The advanced anti-spam solution for IMail mailservers. >Declude Virus: Catches known viruses and is the leader in mailserver >vulnerability detection. >Find out what you've been missing: Ask about our free 30-day evaluation. > >--- >[This E-mail was scanned for viruses by Declude Virus (http://www.declude.com)] > > >To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html >List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ >Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/ > To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/
