Email sending method based on the scalable message online protocol and credit mechanism belongs to the network security area. Its features are as follows: this method utilizes the IM platform based on the XMPP protocol to effectively guarantee the true source identity. The 'pull mode' transmission mode is used in the Email sending. The IM platform is used to maintain the characteristics of the online status of the user and the block transfer mode is combined with the direct transfer mode between the sender and receiver in the message transfer. The method invents the distinct combination mechanism of the credit mechanism and blacklist policy and can real time prevent the rubbish message attack. The method can be deployed on the IM platform based on the XMPP protocol which is extensively used now. The method adopts the server forwarding and end-to-end direct message transfer solution, so it can alleviate the load of the old server and can not affect the performance of the old IM service.