What does AWeber do with undeliverable subscribers?
When an email address is undeliverable due to a bounce, the entry is flagged in your account under the subscriber's profile. You can also view all bounces for the list from the "Undeliverable" filter on the "Subscribers" page.
We will continue to send messages to a subscriber until they have been undeliverable more than 3 times in more than a 7-day period. If a subscriber has bounced 3 times in that 7-day period, they will be unsubscribed on the next (or fourth) bounce after the 7 day window is concluded.
This process will reset every 6 months. So, if a subscriber is undeliverable 3 times in a 7-day period and then does not bounce for another 6 months, they will not be unsubscribed. After the 6-months period have ended, this process resets and a subscriber will need to be undeliverable more than 3 times in a 7-day period to be unsubscribed.