Strategies for Symbiotic Marketing

So, when marketing symbiotically, how would you approach something like a receipt mailing?

Some nonprofits mail a tax receipt as a stand-alone because it’s cheaper than including a letter. Others enclose a thank-you letter with generic content — they don’t want to spend the time and money to create a special note of appreciation. Others still figure that, since they’ve already incurred the cost of postage, they might as well ask for another donation at the same time.