In the order they arrived, from the first email after signup.
How often, when and how Trello emails its subscribers, measured from every email we received.
Every email Trello sent in its first month, grouped by the day it arrived.
Every subject line and preview text, in the order they arrived.
We captured 2 emails from Trello after signing up: account verification and trial ending emails.
All of its emails arrived on the day we signed up, it sends with Amazon SES, its designs lean blue and purple and 50% of its emails use plain text.
Its subject lines run about 29 characters.