Mail delivery agent

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).

Many Mail Handling Software products bundle multiple message delivery agents with the message transfer agent component, providing for site customization of the specifics of mail delivery to a user.

On Unix-like systems, procmail and maildrop are the most popular MDAs. The (LMTP) is a protocol that is frequently implemented by network-aware MDAs.

The mail delivery agent is generally not started from the command line, but is usually invoked by mail delivery subsystems, such as a mail transport agent, or a mail retrieval agent.

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