It is indeed a pity that this project has finished, it was my favourite project for my mobile. On the other hand it is really great that project has reached its goals.

Greylisting is already being discussed on Slack but it can only happen with the set criteria are met. According to @G_UK in terms of actual greylisting:

It's very hard to estimate at the moment, what I can say is that it would be no less than say 3-4 days.