Reza

One job per email is right and it is much harder than it sounds. Everything wants to be added to the first one.

Four emails, measured each one, and the result that surprised me: the last two did nothing measurable and the second one did almost all of the work.

The second was sent only to people who had signed up and not completed the first setup step, and it contained that one step and nothing else. Triggered rather than scheduled, one job, and it moved completion by a meaningful amount. The scheduled ones were noise.