I have had a number of conversations with entrepreneurs recently where it became clear that their own personal dislike for email/twitter/Facebook/mobile notifications stood in the way of growth. It would be nice to think that you could build a service that is so awesome that everyone who discovers it will (a) instantly get all their friends to use it and (b) keep coming back all the time. But that rarely happens. Instead, there is a lot more evidence to suggest that it is much harder to err on the side of over-notifying/over-promoting than under-notifying/under-promoting. Facebook and Zynga are both great examples of this. I strongly believe users should have an ability to opt-out, skip, turn-off, etc. But burying steps such as sharing on Twitter, or inviting friends via email, or not sending out newsletters or email notifications by default out of a sense of not wanting to be too spammy (much as I appreciate this sentiment) is a mistake. On mobile that most likely means having push notifications and integrating with the address book and using that as another way to discover presence of friends on a service and allow for invitations. As PT Barnum said so memorably: “Without promotion something terrible happens,” he said. “Nothing!”
