Please, don't ban anonymous account, there are at least couple people who regularly use it. It is rare that anyone would use it for voting, it was the first time I have logged in and noticed so much upvoting and downvoting in a single thread. Sometimes I find a couple of votes in a thread, and I often revert them, but that's it. Maybe there were previous incidents in the past, but I haven't noticed them. Of course, things like that relies on goodwill. If someone started abusing it, there would be no choice except to ban it.
By the way, thank you Nancy. You do a job that is often unpleasant, but necessary.
I've gotten sufficient evidence from support that voiceofra has been doing retributive downvoting. I've banned them without prior notice because I'm not giving them more chances to downvote.
I'm thinking of something like not letting anyone give more than 5 downvotes/week for content which is more than a month old. The numbers and the time period are tentative-- this isn't my ideal rule. This is probably technically possible. However, my impression is that highly specific rules like that are an invitation to gaming the rules.
I would rather just make spiteful down-voting impossible (or maybe make it expensive) rather than trying to find out who's doing it. Admittedly, putting up barriers to downvoting for past comments doesn't solve the problem of people who down-vote everything, but at least people who downvote current material are easier to notice.
Any thoughts about technical solutions to excessive down-voting of past material?