The irony is you're using a public platform to apologise for this, whereby people chose to come - it's not been foisted upon them. I'd imagine it gained you quite some interest in the project at first. You could have used the same means with some extra content to make the click worth it. This just looks sketchy and you may have alienated a number of potential users. Yes it's only an email but the demographic here is a little different to the norm.