What I was trying to ask is whether your IP address was different before you started getting the error than after getting the message. Sometimes your ISP changes your IP address at rare intervals, or else someone with a nearby IP address caused Undernet to create a wildcard range gline.
When I googled the message beginning with the word 'infected' I got quite a few hits, many of them from 2012 or earlier, but the top hit was an Undernet link where they give an email address for an appeal.
