"Ok, I got it" is an inbox cleaning tool. "Ok, I got it" is only used to remove an email from the inbox. It keeps the contact in their current status. So, if they were in a campaign and you selected "Ok, I got it" they will remain in the campaign and continue to get campaign emails.
You can also use "Ok, I got it" to remove an email from a contact that is already in a reply action. For example, if you scheduled a cycle or follow up and the contact replied with a "thank you". No need to reply or schedule another action, simply use "No Action" to remove that reply and keep the contact in the Cycle or Follow Up you had scheduled.
The only messages that should be in this "Ok, I got it" section are Out of Office Replies and System Messages. All other messages should be dispositioned as Meeting, Follow Up, Cycle, Inactive or Remove. If you have used the "Ok, I got it" status in error, simply click on the message, select "Response" and choose the appropriate reply action. Remember, "Update" does not send the initial reply but updates the contact and schedules future activity. "Send" does the same thing AND sends the initial reply.