A mail retrieval agent (MRA) is a computer application that retrieves or fetches e-mail from a remote mail server and works with a mail delivery agent to deliver mail to a local or remote email mailbox.
[1] MRA is an automated agent that works on behalf of the user agent checks for the new incoming mail.
Significant examples of standalone MRAs include fetchmail and getmail.
[4][user-generated source] The concept of an MRA is not standardized in email architecture.
Although they operate like mail transfer agents, MRAs are technically clients when they retrieve and submit messages.