A mail retrieval agent (MRA) is a
computer
A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...
application that retrieves or fetches
e-mail
Electronic mail (usually shortened to email; alternatively hyphenated e-mail) is a method of transmitting and receiving Digital media, digital messages using electronics, electronic devices over a computer network. It was conceived in the ...
from a remote mail server and works with a
mail delivery agent
A message delivery agent (MDA), or mail delivery agent, is a computer software component that is responsible for the delivery of e-mail messages to a local recipient's mailbox. It is also called a local delivery agent (LDA).
Within the Internet ...
to deliver mail to a local or remote
email mailbox. MRA is an automated agent that works on behalf of the user agent checks for the new incoming mail. MRAs may be external applications by themselves or be built into bigger applications like a
mail user agent
The mail or post is a system for physically transporting postcards, letters, and parcels. A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century, national postal sy ...
. Significant examples of standalone MRAs include
fetchmail and
getmail.
MuttWiki: MailConcept
/ref>
The concept of an MRA is not standardized in email architecture. Although they operate like mail transfer agent
Within the Internet email system, a message transfer agent (MTA), mail transfer agent, or mail relay is software that transfers electronic mail messages from one computer to another using the Simple Mail Transfer Protocol. In some contexts, the a ...
s, MRAs are technically clients when they retrieve and submit messages.
Delivery mechanisms
The mail retrieval agent may support delivery of retrieved mail via the following mechanisms:
* Via a mail transport agent (Listening for SMTP
The Simple Mail Transfer Protocol (SMTP) is an Internet standard communication protocol for electronic mail transmission. Mail servers and other message transfer agents use SMTP to send and receive mail messages. User-level email clients typi ...
transfers on port 25)
* Via a mail delivery agent
* Direct delivery to an mbox
Mbox is a generic term for a family of related file formats used for holding collections of email messages. It was first implemented in Research Unix, Fifth Edition Unix.
All messages in an mbox mailbox are Concatenation, concatenated and store ...
formatted mailbox
* Direct delivery to a maildir
The Maildir e-mail format is a common way of storing email messages on a file system, rather than in a database. Each message is assigned a Computer file, file with a unique name, and each mail folder is a file system directory containing these fil ...
directory
* Output to standard output Standard may refer to:
Symbols
* Colours, standards and guidons, kinds of military signs
* Standard (emblem), a type of a large symbol or emblem used for identification
Norms, conventions or requirements
* Standard (metrology), an object t ...
Multiple mailbox support
The mail retriever agent may support retrieval of mail from multiple mailboxes simultaneously. This enables a mailserver to have a centrally configured mail retriever agent that runs against a dedicated mail system account, and collects the mail for all users in a single invocation (rather than using cron
The cron command-line utility is a job scheduler on Unix-like operating systems. Users who set up and maintain software environments use cron to schedule jobs (commands or shell scripts), also known as cron jobs, to run periodically at fixed t ...
to run a mail retriever agent against all the mail recipients).
See also
* Email agent (infrastructure) (MxA)
References
Bibliography
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Email agents
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