Spam

Another 19 months have passed since my last report from the spam front. This time the news is not so good.

Although the overall spam rate has dropped again, for the third time in a row, and is now at 11 messages per day (down from 14 messages per day), the other side of the medal is that SpamAssassin's recognition rate has also dropped for the third time in a row. This time the drop has been so marked that it has overcome the benefits of the spam rate drop, causing the average number of spam mails that have made it into my inbox to increase to 1.6 messages/day (up from 1.4 the last time).

This is the first increase of that all-important figure since I switched to greylisting almost 5 years ago! This turnaround is slightly scary because it means that for the first time ever spammers have actually become better in getting their junk into my inbox. I refuse to be overly alarmed at this point, and I hope that this trend will not continue, but if it does I will have to consider new measures, such as starting to use blacklists.

For more statistics details, see this wiki page.

It is now 2½ years since my last post on greylisting, and over 3½ years since I reluctantly started to use this spam prevention technique. I am pleased to report that greylisting remains as successful as it was on day one.

In fact, the situation has even improved since that last post 2½ years ago: The overall spam rate has dropped from 36 to 14 messages per day! It is unclear whether the reason for this is a world-wide decrease in spam mails, or a decrease in "quality" of spam mails, i.e. fewer spam mails make it past the greylisting wall. I don't need to know the exact reason, though, to feel happy about the result: Due to the low overall spam rate, on average only 1.4 messages per day now make it into my inbox. Wow, these days I can even leave my mailbox unattended for a few days without getting flooded - isn't that great?! (compare the current situation to when I only had Spam Assassin and, at the peak, my inbox was inundated by more than 40 new spam messages per day).

For more statistics details, see this wiki page.

In September 2009 I started to use greylisting after the spam rate on my main email address had reached an unbelievable 1200 messages per day. Here's the article that describes the event, the reasons why I avoided greylisting for a long time, and why I finally had to give up my resistance.

It is now 15 months later, and I just added an entry to my spam statistics page which makes me a very happy email user! The spam deluge has been reduced to a trickle of merely 36 messages per day, of which almost 95% are correctly recognized as spam by SpamAssassin. If ever there was a success story, greylisting at herzbube.ch is it!

After the break there is a little timeline that might be interesting to read. It is essentially a summary from the statistics page linked above.

Yesterday I finally had enough! The spam situation had escalated to such a painful level that, even though I had long tried to avoid it, at last I made the decision to configure my system to use greylisting. Using the Debian package greylistd and studying this excellent HOWTO, I was able to whip up a suitable configuration for my MTA (Exim) in a very short time. After a few manual tests I let the experiment go live, and waited...