Self-serve SaaS trial. Sent at signup.
Hi {{first_name}},
Welcome to {{ProductName}}.
Start here: {{first_action_link}}
Estimated time: {{time_estimate}}.
Reply if anything looks broken.
{{Sender name}} One next action. Time estimate. Reply invitation. Job: get them logged in and to first action.
Single CTA. Time estimate. Founder line for first 1,000 users.
Listing every feature.