The question behind the term
A message service needs enough state to authenticate accounts, route events, synchronize devices and enforce membership. Privacy work begins by explaining why each field exists and deleting the fields that cannot justify their cost.
A reviewable approach
Draw the data flow from composition to device encryption, transport, persistence, notification, backup and deletion. Treat direct content, community content, media, search indexes and operational logs as separate stores with separate retention rules.
- Inventory every store and derived index
- Set retention by data class
- Keep message text out of telemetry
- Make deletion and export behavior explicit
The boundary to keep visible
Data minimization is not anonymity. Account-based delivery can still expose social and timing metadata, and notification providers may receive routing tokens even when they do not receive message text.