In January 2013, Gentry Underwood launched an email app called Mailbox that was acquired just 37 days later.

How?

1. They focused on solving one massive problem – tons of unread messages in email inboxes.

2. They created a smart and simple solution.

3. They created an automated “referral reservation scheme”:

3.1. You sign up to get notified when the app will become available to you.

3.2. You see how many people are in front of you in the queue.

3.3. The system notifies you: the more friends you invite, the higher you’ll be in the queue, the faster you’ll get access to the app.

3.4. You invite your friends, and they invite their friends, … etc.

4. They created a simple video that went viral (because the problem was hot/unsolved and the solution was elegant).

5. They notified tech media, who were more than happy to write about the app (because the problem was hot/unsolved and the solution was elegant).

6. The virality of the video met media coverage, got multiplied by the “referral reservation scheme” and in 37 days resulted in 538,000 users waiting in a line to get access to the app.

7. 37 days later Dropbox acquired it for a reported $100 million.