Email spam also known as junk email, is a huge annoyance for end users and a huge problem for service providers like ourselves. Lately, we’ve seen a big increase in the number of spam emails which have been making their way to our customers’ mailboxes. In the last few hours we’ve completed some changes which we believe will significantly reduce spam.
NitroSell makes use of DNS Blackhole Lists (DNSBL) to help combat spam arriving at our mailservers. DNSBL maintains a list of IP addresses which are known to be the sources of spam on the internet. Every time our mailserver receives a connection from host on the internet, it looks up the remote IP address on all of the configured DNSBL’s. If the IP is found to be blacklisted, the connection is rejected, otherwise things continue normally. Sometimes blacklisted IP’s are dedicated spamming machines, other times these can be hosts which have been compromised and become hijacked for the purposes of sending out millions of millions of spam emails. Compromised hosts can be servers or even home and office PC’s.
To help combat this problem, we have now implemented an additional DNSBL on our mailservers which blocks emails originating from end-user IP address ranges. These IP addresses should never be delivering unauthenticated email to any internet mail server except for those provided specifically by their ISP. From what we’re seeing so far these changes have made a big difference!
End-user IP address ranges also include the IP addresses that you, our customers, send email from. Fortunately, we’ve employed some neat tricks to ensure that these changes don’t get in the way of our own customers sending and receiving emails.
No configuration changes are required in order to receive the enhanced spam protection. Hopefully, you have already noticed a big drop in the number of junk email reaching your inbox.