US Patent 11784959 Message transfer agent architecture for email delivery systems

An email message delivery system is described that provides a fast and reliable managed email delivery service using MTAs and proxy servers. An email message is selected by an MTA for processing. The MTA determines a sender and an intended recipient associated with the email message. The MTA then identifies a pool of usable source internet protocol addresses for the email message based on the sender and selects a particular source IP address from the pool. The MTA then identifies a particular proxy server that is configured to handle the selected particular source IP address and communicates to the particular proxy server, information including the particular source IP address and the destination IP address. The MTA then transmits the email message to the destination IP address using a connection established by the proxy server between the particular source IP address and the destination IP address.