I am sure someone else on this Forum can provide you with good advice, but your question was not clear to me.
If you are referring to gifts from foundations, these funding sources usually require at the very least year-end reports with detailed information on how their gifts were spent. I just have never heard of the practice of sending donors end of the year receipts, but if this is done for income tax reasons, then I suppose it is a good idea and will be appreciated. And by all means, continue to acknowledge gifts as they are received.
