Dear Mr. Zhang and Mr. Mai, 

Greetings and I am happy to let you know hat I have received my Greencard yesterday and I am so happy about it and your timely response, your help in getting the  Green Card. I will certainly recommend your firm to my friends. 

I would love to work with you all again in the future for my citizenship application. Kindly let me know what will the procedure and how long do I have to wait to apply for it, the fees etc. 

Thank you again,