Permission pass
One email to an existing list asking every recipient to confirm they want to stay subscribed, keeping only those who click to confirm and deleting the rest.
What it means
Spamhaus describes a permission pass as sending a new bulk email asking recipients to confirm that they wish to remain subscribed: only those who click the confirmation link stay, and those who do not answer or whose addresses bounce are deleted. The result is a confirmed opt-in list.
Spamhaus limits it to otherwise opt-in lists that have become slightly dirty, for example after an insecure web form was abused. It is not acceptable for harvested, purchased or rented lists, which Spamhaus treats as spam. It must be opt-in, never asking people to reply in order to be removed. If the list is already blocked, coordinate with the blocking filters first; Spamhaus says it will normally help if the effort is genuine.
M3AAWG also recommends a permission pass to turn implied consent into explicit consent.
Related terms
Sources
What this definition rests on. The wording is ours; the facts are theirs.
All 432 terms in the glossaryThe wiki: blocklists and bounce codes