Rebuild the missing context
Assume the recipient will not remember every date, promise, or earlier conversation. For a message about how to invite an old friend to a birthday party, use this factual base: give the event, date, location, relevant history, and what kind of contact the invitation involves.
Say what needs to happen next
State the decision, information, or practical action you need and include a real deadline only when one exists. Offer a simple way to accept, decline, ask a practical question, or choose a lower-contact option. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Avoid making urgency into pressure
Do not announce their attendance, use relatives to persuade them, or make a public gesture before they agree. Respect no-contact, venue safety, custody, and legal restrictions even when the event feels important. Do not make the other person responsible for reducing the discomfort that prompted you to write.