<p>I want to let the university’s admission committee know that my reference changed his contact number because he doesn’t have an office anymore (the number was for his office). How can I create a nice, formal e-mail for them?</p>
<p>You don’t need to make it complicated. Short is better since they are likely get tons of panicked emails about now. Just sent them a short note to update them on this specific piece of information. If there is anything else significant that has happened since you submitted your application, you can also mention that (national or state level award, just learned you are the lead in the school musical, just invited to Olympic tryouts … dramatic examples).</p>