I think it means to get revenge on somebody - usually a company - by sending spam in their name. The company will receive complaints from lots of angry people and ofcourse do their best to explain. But if the number of complaints is large enough they will never have the time to catch up and their reputation will be ruined. In the worst case the site will be taken down.

If I remember it right the word “joe job” originates from the domain it was first targeted at.

Not so much “personal” as it represents someone who actually knows someone else (and decides to let spamming commence based upon that type of ‘personal’ as in an actual relationship gone bad or even bad from the beginning), but “personal” in the sense that spammers appear to select users and their sites by following user links/references based upon starting points of a selective type: conservatives are spammed by the porno/gambling crud and similar.

Other issue: what is a “joejob”?

In an ideal world, they’d see the warnings you’ve got. But for some reason (understanding it is beyond me) they blink right past those and blast away with their flames.

I think the best thing you can do is *not* to take that personally.