Name the impact without exaggerating it
Describe who had to wait, worry, redo work, spend money, or make a choice with incomplete information. For a message about how to thank a volunteer for their time, use this factual base: name what the person did, when it mattered, and the practical or emotional difference it made.
Make repair practical
Offer the repair you can actually complete, with ownership, timing, and any limit stated honestly. Thank them directly and share one honest outcome they helped make possible. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Let future behavior carry the proof
Do not exaggerate, create a public spotlight without consent, or attach a new favor to the same message. Protect private health, financial, workplace, and family information when describing their help. A promise inside a message is weaker than a visible change in what you do after it.