How to handle bounced unsubscribes?

A "bounced unsubscribe" occurs when you send an unsubscribe confirmation email and it bounces, or when someone attempts to unsubscribe from an address that's already bouncing on your regular sends. This creates a logical puzzle: how do you confirm unsubscription to someone you can't reach? The answer is straightforward-process the unsubscribe regardless of the bounce. The subscriber's intent to opt out is clear; the bounce is a separate technical issue that doesn't invalidate their request.

From a practical standpoint, bounced addresses on unsubscribe attempts should be handled through your normal suppression process. Add the address to your suppression list with the unsubscribe designation, even though you couldn't deliver a confirmation. If the address was already on your bounce suppression list (due to previous hard bounces), it remains suppressed-now for two reasons. There's no need to remove bounce suppression to send an unsubscribe confirmation; the address was already not receiving mail, and the unsubscribe ensures it stays that way even if the mailbox later becomes active again.

The edge case worth considering is soft bounces on confirmation emails. If someone unsubscribes and your confirmation email soft bounces (temporary failure), you might retry the confirmation a few times as you would any transactional email. However, the unsubscribe itself should be processed immediately regardless of whether the confirmation is successfully delivered. Don't hold unsubscribe processing hostage to confirmation delivery. The usubscriber's request is valid even if you can't acknowledge it. An unsubscribe request doesn't require successful confirmation to be valid-process it immediately and let the confirmation be a courtesy, not a condition.