Reclaim the inbox and clear what they planted
Order matters: kill sessions and reset password before warning anyone. If you email contacts while the attacker still has access, you're warning the attacker, not your contacts.
Common attacker artefacts to remove
- Forwarding rule named like 'Inbox' or 'Junk' (sounds innocuous)
- Filter that auto-deletes replies from your bank or accountant
- OAuth grants to unknown 'mail' or 'productivity' apps
- Delegated mailbox permissions you didn't set