Issue with sending mail from server

Issue with sending mail from server

I have an application running which sends from my domain. Recently (in my application) I am getting this error:

DeliveryError: Message delivery failed: 554 Relaying disallowed

This was not happening till I started getting the issue where I couldn't receive messages (which is still happening). 
DeliveryError: Message delivery failed: 553 Relaying disallowedDeliveryError: Message delivery failed: 553 Relaying disallowed
DeliveryError: Message delivery failed: 553 Relaying disallowedDeliveryError: Message delivery failed: 553 Relaying disallowedDeliveryError: Message delivery failed: 553 Relaying disallowedDeliveryError: Message delivery failed: 553 Relaying disallowedDeliveryError: Message delivery failed: 553 Relaying disallowedDeliveryError: Message delivery failed: 553 Relaying disallowed
Message delivery failed: 553 Relaying disallowed

Message delivery failed: 553 Relaying disallowed