I agree that its a good idea to remind people what you do, especially if it takes a long time between the sign up and launch (or further communication between parties). I just put up a landing page for my startup and think I did a decent job conveying what the company does, but I'm curious, but how much is necessary to remind them (in future communications)?

Is a one-liner enough (i.e. "We're a crowd-sourced record label!"), or would people prefer the whole spiel (i.e. "We're a crowd-sourced record label that does this, this and this!")?