What is the function of a Mail Delivery Agent (MDA)?

A Mail Delivery Agent (MDA) is primarily responsible for the final delivery of email messages. Its main function is to accept incoming email messages from a Mail Transfer Agent (MTA) and then store those messages in the appropriate mailboxes of the recipients. This means that once an email is sent and travels through various servers, the MDA is responsible for ensuring that the email reaches its intended destination and is stored correctly so that the recipient can access it later.

The other options describe different aspects of email handling. Sending outgoing emails is typically the role of a Mail User Agent (MUA) or MTA. Deleting unwanted emails is usually handled by filtering processes and user actions, not specifically by an MDA. Transferring email from server to server is a function performed by the MTA, which routes and delivers outgoing messages to other servers. Thus, the primary role of the MDA focuses specifically on the final storage and organization of received emails, making the option about storing email in the recipient's mailbox the correct choice.