Autorespond email says its being sent, but submitter is not receiving it.

We have an autoresponse email set up to send a coupon to a customer. But customers are not receiving it. 

The email history queue says it is sent but not being delivered.

I also cleared the form cache and checked if the email address was on the bounce list and its not. 

We were experiencing a larger than normal load on our Email queue that should now be resolved.  Emails should now be sending right away and older emails that were in the queue should now be sent.  There may still be a slight delay with some emails but for the most part everything should be back to normal.