Hi [First name],

Kevin again. It's been a few days, so I wanted to ask properly: is Email Bump working for you?

If it is, I'd love to hear what you're using it for. If it isn't, I'd rather hear that. What was missing, what was confusing, or what made you stop. That feedback is worth more to me than a polite silence.

Either way, replying to this reaches me directly.

Kevin