A stranger cannot message you. A conversation opens only when one of these is true:
- You follow each other. Mutual follows can talk, both ways.
- You asked for help and they offered. You can message them; they cannot message you first. The person who asked decides whether it becomes a conversation.
- They are helping you, or you are helping them. Open both ways while the request is in progress, and for 14 days after it ends, so loose ends can be tied up.
- Hiring: you showed interest in someone's job post, or they showed interest in yours.
- Admins, so support can reach you.
Once someone has messaged you, you can always reply. A thread that has gone quiet past its 14 days is read-only rather than deleted.