We do acknowledgements usually as Letters not as receipts and we want it to be in a letter format and edit as the way we want it,

In Gifts Receipting section we see the PDF receipt template

We prefer it to be more customized in a letter format than as a receipt which we can edit as the way we want.

And the body section we can only write upto 500 letters where as we write about 1000 letters in the body section. Therefore need to extend the number of characters we can use for a letter as well in this section.