Hi [firstName] –

Thank you so much for meeting with me [& someone] last week. Your feedback is incredibly helpful for our team; it helps us know how to build the best app we can for volunteers!

For example, from your test session, we learned that [1–2 key insights from their test].

[Could you please send us [someone's contact info]? We'd love to reach out!]

Thanks again for all your help – we'll keep you posted of future testing opportunities. Be sure to track your hour helping us test on Unself !

Have a great rest of your week,

– Elizabeth