Once you have sent off the Corrective Action task to your supplier, they will receive it in their inbox (and you can still see it in your outbox).
You can still interact with the task and add to it however by ;
Adding a comment - you can choose to add an internal comment (visible only for your team) or a comment visible to your business parntner
Adding a file - you can add any file attachment, in addition to the file(s) you initially added when you sent the task
Once your business partner has resolved the Corrective Action Task, it will return to you and you will be asked to either :
Acknowledge the resolution by clicking 'Done', in which case the task will be definitively closed
Reject the resolution by clicking 'Reject', in which case the task will go back to your supplier's inbox