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Junk Email is Junk

We’re dropping our use of “Spam DNS Lists”, because we have few positive experiences with it. Frankly, it is Junk.

A service such as Junk Email Filter is supposed to use response values to regular DNS queries that allow services such as Kolab Now to gain some insight as to the reputation of sender domains, email addresses, server IP addresses, reverse DNS host- and domain names, and server HELO names.

Services like these are supposed to be ever so slightly conservative (a single SPAM message should not blacklist the sender, sender domain and sending server), and it is supposed to provide procedures to let entries be removed. It appears to not be conservative, and it doesn’t allow searching for anything but an IP address either.

Furthermore, it appears to fail to use SPF/DKIM/DMARC validation before it goes in to spam filtering mode. It doesn’t seem to provide its zones over DNSSEC (albeit that is a more commonly shared problem).

Certain customers have made us aware of traffic that is definitely legitimate, but would be blocked by Junk Email Filter regardless. The entries under which it would appear to draw such a conclusion are either not available, or false.

So, it’s time to declare it Junk itself, and Trash it.

Thanks to those customers that alerted us to the problem (you know who you are!) and were willing to work with us on the details.

What Does This Mean for Other Customers?

There’s a chance spam traffic will increase ever so slightly, as it is likely fewer senders get blocked. The other way around seems not unlikely either — perhaps some legitimate traffic was getting blocked as well, and you’d now start to be receive that traffic again. Maybe read our Get Spam Out of Your INBOX knowledge base article for tips.