Dear Jerry and Annie,

I'm grateful to the birthday greetings from you and your firm!

I sincerely thank you for your work, helping me to get the green card approved so quickly and efficiently!
Honestly, without your assistance I would be in big trouble staying in the U.S. or continuing my current job.
But as one of the beneficiaries of your firm, I cannot express more than this Thank-You-email.

I am really happy to receive a birthday card from you!

Once again, Thank you!

Sincerely,

Client