“Get together?”

The subject line of the e-mail was like every other come-on that hit Jan Koum’s in-box in the spring of 2012. He was pounded daily by investors who wanted a piece of his company, WhatsApp. Hatched on his birthday, Feb. 24, 2009, WhatsApp was emerging as a global phenomenon. Some 90 million people were using it to text and send photos for free. No social utility had ever grown as fast. Facebook had only 60 million by its third birthday. And at the time close to half of WhatsApp users were returning daily.

Koum looked at the e-mail sender: Mark Zuckerberg. Now, that was a first. The Facebook founder had been using WhatsApp and wanted him over for dinner. Koum stalled, then finally wrote back saying he was traveling soon and dealing with server issues. Zuckerberg suggested they meet before Koum left. Koum forwarded the reply to his cofounder, Brian Acton, and his sole venture backer, Jim Goetz, a partner at Sequoia Capital, adding the word: “Persistent!”

Take the meeting, Acton said: “When someone of Mark’s status contacts you directly, you answer the phone.”

This is a fascinating read.