Mail Delivery Agent (MDA)
A mail delivery agent or message delivery agent (MDA) is a computer software component that is responsible for the delivery of e-mail messages to a local recipient's mailbox. Also called an LDA, or local delivery agent.
Within the Internet mail architecture, local message delivery is achieved through a process of handling messages from the message transfer agent, and storing mail into the recipient's environment (typically a mailbox).
An example of MDA software would be Dovecot.