Extension:FundraisingEmailUnsubscribe

Details
This extension renders a form to allow users to opt out of receiving future Wikimedia Fundraising solicitation emails by clicking a link in a donation receipt.

Special:FundraiserUnsubscribe looks for three parameters on the query string:
 * 'c', the contribution id that triggered the donation receipt
 * 'e', the donor's email address
 * 'h', a validation hash. This is calculated using, which should be configured to match   in the drupal module which sends the receipts.