Anybody Using Event Driven Email?

Is anybody using event driven email for their membership sites? It seems like there's a lot of opportunity using more sophisticated email marketing with membership sites. I've been using customer.io for my SAAS app, and I've been pleased with the results. If anyone is interested, I could help you integrate event driven email into your system. I'd do it for free, if I can write a case study about it after.

is this an idea or you actually had possitive results before?