Once set to Bounced, Marketing Cloud stops trying to deliver only that email message which bounced. It'll try again with the next email (depending on subscriber status)
A Hard Bounce happens as soon as Marketing Cloud detects a permanent condition and the subscriber status is changed to 'Bounced'. Marketing Cloud will not make any more tries to deliver that particular email message.
If the subscriber's status was already Bounced, which indicates they had experienced a bounce previously, the application treats the bounce differently. If the Subscriber status is 'Bounced', then next email message will be tried (if it is the first or second email). If the bounce happens on 3rd email also, then it is set to 'Undelivered'.
Once set to Undelivered, Marketing Cloud will never send any more emails to the email address.
Yes, you need that exclusion list for Hard Bounces because Marketing Cloud will continue to try until the status changes to 'Undeliverable'
I understand the documentation language is a little ambiguous but the key things to note is -
- If Bounced, no more tries happens for the current email
- If Bounce Count is 1 or 2, next email will be tried
- Once it hits 3, it will be set to Undeliverable based on some conditions (last 15 days bounces)