We now have donor numbers to help you track your donors, especially if your donors use an envelope number system. You can create as many lists of donor numbers as you need. Each list has an effective (starting) date.
In the donation entry screen, you can then pick your donors based on either the donor's name or donor number.
Donor numbers are included on contributions statements, and there is a new report — Donor Number List — that shows you a list of all donors tho whom you've assigned a number.