Comments on: Spam fighting techniques using Sendmail

By: Patrick Vande Walle

Patrick Vande Walle — Wed, 16 Mar 2011 08:10:01 +0000

@Kaisar

It depends what you mean by “valid IP address”. The above-mentioned ruleset catches connections from hosts that advertise only private IP space (aka RFC1918) as MX records.

If you want to check that the IP address matches the host name, you could use the rDNS ruleset mentioned above. Although this is mandated by RFCs, do expect a lot of false positives. Many hosters do not update rDNS records nowadays. I personally would not use that ruleset anymore.

This being said, this is a very old post of mine. I have switched to Postfix more than 3 years ago. Hence, my experience with Sendmail is becoming outdated.

By: Md.Kaisar Ahmed Khan

Md.Kaisar Ahmed Khan — Wed, 16 Mar 2011 04:02:42 +0000

Check for valid IP addresses how can i use above mentiond script to check validiaty of IP. in sendmail.mc file or to other file.

lipson12@yahoo.com

By: Andy Lee Robinson

Andy Lee Robinson — Wed, 02 Feb 2011 02:48:17 +0000

Useful tips, and SPF and DKIM take up rates are still really pathetic. What more can we do to get everyone using them?

You would think that all banks would want to protect their domains from spoofing. Paypal still use old domain keys and spf soft fails (~all).
hmrc.gov.uk doesn’t have any SPF at all and I am sick of phishing spam. Complaining to them had no effect!
Of course, having spf and dkim records are useless unless the receiving MTAs bother to check and reject!