An email client (or mail user agent [MUA]) is a computer program that is used to read and send e-mail. // A computer program or software program (usually abbreviated to a program) is a step-by-step list of instructions written for a particular computer architecture in a particular computer programming language. ... Wikipedia does not yet have an article with this exact name. ...

Originally, the MUA was intended to be just a little programm to read the messages, which the MDA in conjunction with the MTA would transfer into a local mailbox. A Mail Delivery Agent (MDA) is software that accepts incoming e-mail messages and distributes them to recipients individual mailboxes (if the destination account is on the local machine), or forwards back to an SMTP server (if the destination is on a remote server). ... A mail transfer agent or MTA (also called a mail server, or a mail exchange server in the context of the Domain Name System) is a computer program or software agent that transfers electronic mail messages from one computer to another. ...

The most important mailbox formats are mbox and Maildir. These rather simple protocols for locally storing emails make import, export and backup of mailfolders quite easy. Mbox is the name for several different things, including an electronic mail file format. ... Maildir is a format for an e-mail spool that does not require file locking to maintain message integrity because the messages are kept in separate files with unique names. ...

Emails to be sent would be handed over to the MTA (perhaps via an MSA, therefore an MUA would not have to provide any transport-related functions. A mail submission agent or MSA is a computer program or software agent which receives electronic mail messages from a mail user agent (MUA) and contacts an mail transfer agent (MTA) for delivery of the mail. ...

Since the various Windows versions intended for home use never provided an MTA, most modern MUAs have to support protocols like POP3 and IMAP to comunicate with a remote MTA located at the email providers machine. Microsoft Windows is a range of operating environments and operating systems for personal computers and servers. ... Post Office Protocol version 3 (POP3) is an application layer Internet standard protocol used to retrieve email from a remote server to a local client over a TCP/IP connection. ... The Internet Message Access Protocol (commonly known as IMAP, and previously called Interactive Mail Access Protocol) is an application layer Internet protocol used for accessing email on a remote server from a local client. ...

IMAP and the updated IMAP4 are optimized for storage of e-mail on the server, while the POP3 protocol generally assumes that the e-mail is downloaded to the client. The SMTP protocol is used by most email clients to send e-mail. The Internet Message Access Protocol (commonly known as IMAP, and previously called Interactive Mail Access Protocol) is an application layer Internet protocol used for accessing email on a remote server from a local client. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for email transmission across the Internet. ...

In addition to the fat client email clients (or small MUAs in cooperation with a local MDA/MTA) presented here, there are also Web-based email programs ("webmail"). The data itself is stored on the server. ... Graphic representation of the World Wide Web around Wikipedia The World Wide Web (WWW, W3, or simply the Web) is an information space in which the items of interest, referred to as resources, are identified by global identifiers called Uniform Resource Identifiers (URIs). ... Webmail is a web application that allows users to read and write e-mail using a web browser or in a more general sense an email account accessed through such an application. ...

An important standard supported by most email clients is MIME, which is used to send binary attachments. Attachments are files that are not part of the e-mail proper, but are sent with the e-mail. Multipurpose Internet Mail Extensions (MIME) is an Internet Standard for the format of e-mail. ...

MAPI (Messaging Application Programming Interface) is a proprietary Microsoft Windows API which can be used to access the Microsoft Exchange email server or to interact with the Microsoft Outlook client. MAPI is an acronym for Messaging Application Programming Interface. ... Microsoft Windows is a range of operating environments and operating systems for personal computers and servers. ... API with 3 clients, using the Unified Modeling Language notation An application programming interface (API) is a set of definitions of the ways one piece of computer software communicates with another. ... Microsoft Exchange Server is a collaborative software server from Microsoft, positioned as a rival to the Lotus Notes / Domino server from IBM. The use of Microsoft Exchange is very widespread in large corporations using Microsoft infrastructure solutions. ... A mail transfer agent or MTA (also called a mail server, or a mail exchange server in the context of the Domain Name System) is a computer program or software agent that transfers electronic mail messages from one computer to another. ... Screenshot of Outlook 2003 Microsoft Outlook is a personal information manager from Microsoft, and is part of the Microsoft Office suite. ...

Javamail, part of the platform-independent Java API, can be used to develop email clients or servers using any of the standard email protocols. Java is an object-oriented programming language developed primarily by James Gosling and colleagues at Sun Microsystems. ...

See also

• List of email clients
• Comparison of email clients
• Unicode and Email