Dear Mr. Mai,
I am gald to work with you. As you know, I played a role as a senior sales manager at XXXX so I always take into consideration about personal relationship because he/she will be my customer some day. Dr. XXXX introduced you to me on Aug. 2014 and finally we made a contract for green card application. Thank you for your great support and look forward to hearing good news from USCIS.
Have a nice week and keep in touch!
All my best,
Client
03/08/2016