Delivery Notification: Delivery has failed ,

Delivery Notification: Delivery has failed ,

Respected sir,

I am getting error
1) Your message cannot be delivered to the following recipients:
     Reason: Over quota

2) Email Outgoing Blocked
 Daily Mail Bounce Count Exceeds Limit [ Bounce count=20 ]
How to increase Daily Mail Bounce Count Exceeds Limit?
sometimes I Have to send many mail. so please help to solve this issue.

3) Undelivered Mail Returned to Sender

Please Help as soon as possible.