That's really odd, because Tinder is not known for the "swipe left or right" aspects of their app, more for their reputation as a sex hook-up app.

My confused impression when I read the title was "A sex hook-up app that uses e-mail?"

Bwa ha ha ha ha. I guess the perception is different depending on where you're from. I immediately thought of the swipe left/right aspect - though I'm in a community that is more chaste than most though. For example, I know a couple who met through tinder without any sex before marriage. That's probably why I thought different - I just really haven't known enough people who use tinder like you described. Or used tinder at for that matter.

edit: minor spelling corrections.

To kids my age (lower 20s) swiping is absolutely linked with tinder.

To kids my age (~40) it's the only thing I know about it as the [UK] media regularly references "Tinder" and "swipe left" [dismiss?].