Start with the part that is verifiable
Separate the event you can describe from the motive or reaction you are guessing. For a message about how to reconnect with an old exchange student friend, use this factual base: introduce yourself with one shared place, activity, person, or time period they can recognize.
Make one answerable request
Give the recipient one concrete question or next step instead of several emotional jobs at once. Offer a low-pressure way to confirm the connection and share a brief reason for reaching out. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Leave the recipient in control
Do not assume old closeness, demand memories, or ask for personal details before they verify who you are. Respect privacy, identity uncertainty, and any refusal, and avoid contacting a minor without a guardian-appropriate route. A clear message remains useful even when the answer is no or no answer arrives.