Really old school, but why not stick plain old cash in an envelope? Make sure that the envelope contents are not visible (eg, wrap the bills in plain paper), an

Really old school, but why not stick plain old cash in an envelope? Make sure that the envelope contents are not visible (eg, wrap the bills in plain paper), and mail the envelope to the charity. Put a fake return address if you want. Explain in the enclosed note that the return address is made up. Or use the name of someone real - they will get a surprise tax receipt. Yes there is a slight risk that someone in the delivery chain will open the envelope and steal the money, but I suspect the chances of this happening (at least here in Canada) are slim, especially if the envelope is inconspicuous. Cash is still the ultimate way to make anonymous transactions.