Every app sends email nobody thinks about until it fails to arrive: the password reset, the receipt, the shipping notice. SendGrid made sure those messages got through. Developers added a few lines of code, and SendGrid handled the servers and the hard work of staying out of spam folders. When the Denver company went public in November 2017, developer tools sold through an API were a proven business, and Twilio had shown the way.

Email Without the Blacklists

Isaac Saldana, Jose Lopez and Tim Jenkins founded SendGrid in 2009 and went through the Techstars accelerator in Boulder. The bet was that developers hated running their own email servers. Getting mail delivered meant constant fights with spam filters and blacklists. SendGrid turned all of that into a service. Developers paid by volume, so the company grew as its customers grew. It later added marketing email tools for newsletters and campaigns.

A Year Later, Twilio Called

SendGrid priced its shares at $16 in November 2017 and began trading on the New York Stock Exchange on November 16, under the ticker SEND. It stayed public for about 14 months. In October 2018 Twilio, which sold text and voice tools to the same developers, agreed to buy SendGrid in an all-stock deal worth about $2 billion. The deal closed on February 1, 2019. SendGrid lives on as Twilio's email service.

Cover: Savoy Pigeons, James McNeill Whistler. Art Institute of Chicago, public domain. Chosen for pigeons (messages delivered).