My Spam Record

Starting in March of 2003 I started keeping track of (roughly) how many spam messages I get a day. I use SpamAssassin to filter my emails, and then I clean out the spam folder every morning at around 9 AM. Since I'm spending the time checking for false positives and then deleting them, it's almost no extra work at all to record the number of spams I actually received. Below, I've plotted the data to date.

Note that there are a couple of caveats on these statistics:

1. I don't always check at exactly the same time. When I'm away, I often make a rough cut where the 9 AM cutoff belonged.
2. These "spams" technically include a fair number of virus messages. SpamAssassin and I both don't really pay much attention to the difference when filtering. However, experience suggests that the majority of the messages are commercial and not virus-generated. (This rule is periodically violated during peak virus-times and those stand out rather clearly in the data.)

I've also plotted two smoothed curves. (The smoothing was done with a "running box" averages of two difference widths.) Note that the regression fit starts at about 14 spams/day and increases at a rate of 1 spam/day every 4 days.

Additional note (1 Sept. 2004) — You'll notice that starting this past June, the spam rate dropped considerably. This is because CU's ITS started doing extra filtering on incoming mail with spam-like characteristics. As you can see, they were eminently successful.

I moved to CICLOPS in May of 2005. For quite a while afterward, my CU account was still my main source of spam. That's dying down, however. Most of my spam comes in through Gmail now, although it almost all gets filtered into my spam folder correctly.

Days of the Week

How does this spam break down by, say, day of the week, you ask? Good question!

As you can see, the spammers take the weekend off, but not by a whole lot. (It's statistically significant, I think, but the effect isn't exactly dramatic.) It's pretty clear that a lot of spam is sent by automated jobs or we have some very dedicated spammers.