上司給了一封讚掦的信,我應該點回應才好呢?

I have been meaning since last week to thank you for your tireless efforts and brilliant work on the xxx. This is really first-rate work and will greatly enhance our celebration of the xxx.
Thanks a lot for your compliment, my contribution to this company is my greatest pleasure.

You can simply make a response verbally:
It's my pleasure.
Or you can reply in writing:
I am more than happy to have your praise, thank you very much for your words.

Just say "Thank you for your support and appreciation."

應該說謝謝