throwawaydev7

It was 2014; impressions dropped by over 96% overnight (essentially, you could find it by searching for the site name, nothing else); the dates didn't correlate with an observed algorithm update; no 'Manual Actions' were showing in GWT; the attendee list at the conference was public.

I'm not comfortable with saying any more because, as hackuser says, I'm not risking the last two years of work (we've finally got back up to that level of Google traffic, though fortunately other traffic has grown immensely). I can simply offer this up and let people disregard it to the extent that they're willing to trust a throwaway account. You don't trust it at all, and that's fine.

Anecdata: At a conference a couple of years ago I was talking on-stage about my product. It's a direct competitor to Google in an area that they don't do very well (quite often, comically badly), and my customers are people who care about getting really good results in this area. I made a couple of joking quips about the poor quality of the Google product during this presentation and moved on.

Two days later my product completely vanished from the Google rankings. No cause that I could think of; I wasn't doing any questionable SEO or other manipulation at the time. I later found out there were Google people at the conference, though I don't know whether they were at the talk or not.

Correlation != causation so I'm hesitant to definitively call shenanigans on this. But it does make me believe ProtonMail's story a little more.