I would
1. stop mail from being processed.
A. disable autocron in Admin panel -> Settings.
B. disable my cron or tash scheduler entry from running.
2. log into the account and delete all the bounce backs.
3. edit the tickets with the wrong address and correct them.
4. if you can wait an hour or so to make sure no more bounces are generated.
5. re-log into the account and delete any new bounce backs emails.
6. turn mail processing back on
A. re-enable autocron in Admin panel -> Settings.
B. re-enable cron or task scheduler.