It's only too bad that SendGrid has struggled to get its marketing email solution off the ground in a meaningful way. If anyone was going to eat MailChimp's lunch, SendGrid would be my choice as top contender. And yet despite SendGrid releasing many iterations of their marketing email solution over the past 5 years they've never seemed to get a lot of success outside of their bread-and-butter transactional email vertical. Their marketing solution brings in less than 20% of total revenue last I heard.