Have a check box for people who ONLY want electronic communications and NOT USPS.
Many organizations are trying to save $$ on print and postage and some donors are now going only electronic. Have an option, part of NetCommunity too, to allow folks to opt-out of USPS and only receive electronic.
You can try to get around this with a solicit code. We use something like "email only" and exclude those records from any paper mailing.