I sometimes sit and watch SPAM attacks coming in on our mail servers. ISPs are constantly having to ward off spam. It is like being in a cyber war. What is mind boggling is that sheer volume. The chart below shows unwanted mail below the x axis and legitimate stuff above.
You can barely make out the legitimate mail because in the scale it is dwarfed by the spam. It is also interesting to observe that the attacks come in waves. You can see the major incoming waves on Sunday evening followed by periodic smaller attacks which appear to be the work of botnets.
This spam is of course not passed on to our customers who pay us for a premium service. You can zoom in by clicking a couple of times on the picture.