[ Thanks to Amy Newman for this link.
“Our postfix server rejects mail like this, because it’s usually
spam. Properly configured mail servers shouldn’t make up bogus
addresses–though a few misconfigured ones do.
“But where do these bogus requests come from? Do they come from
specific countries? How many from .com or .org versus from specific
“To find out, I’ll create a Python dictionary, then use
CairoPlot to plot a pie chart. Each key in the dictionary will be a
top-level domain — for example, “com”; the value will be the
number of rejected messages seen from that domain.”