Q:

We received/had received a letter

I want to acknowledge on receipt of a letter. 
Which one is correct 

"we received" or "we had received"?

And please explain the usages too.
Thanks

A:

In verb tenses "we received" is simple past "we had received" is past perfect.
The simple past is used to describe actions and/or events that are now completed and no longer true in the present.
The past perfect describes completed events that took place in the past before another past event.

