Segment a list by behaviour, then write to each

Here is my user data: {{paste CSV summary — signup date, plan, last active, key actions taken, source}}.

1. Propose 5 behavioural segments that would each get a genuinely different message. Define each with an explicit rule I could write as a query, and estimate its size from my data.
2. For each segment: the belief they currently hold, the single most valuable action for them next, and why generic messaging fails on them.
3. Write one 90-word email per segment, subject included.
4. Name the segments I should NOT message at all and why.
5. Tell me which two segments are worth building automation for and which are one-off manual sends given the sizes.

Don't invent segments the data can't identify. If a segment I'd want isn't measurable, say what to track.