Email is a method of transmitting and receiving messages using electronic devices. It was conceived in the late–20th century as the digital version of, or counterpart to, mail. Email is a ubiquitous and very widely used communication medium; in current use, an email address is often treated as a basic and necessary part of many processes in business, commerce, government, education, entertainment, and other spheres of daily life in most countries.
A graphical user interface, or GUI, is a form of user interface that allows users to interact with electronic devices through graphical icons and visual indicators such as secondary notation. In many applications, GUIs are used instead of text-based UIs, which are based on typed command labels or text navigation. GUIs were introduced in reaction to the perceived steep learning curve of command-line interfaces (CLIs), which require commands to be typed on a computer keyboard.
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 typically use SMTP only for sending messages to a mail server for relaying, and typically submit outgoing email to the mail server on port 587 or 465 per RFC 8314. For retrieving messages, IMAP is standard, but proprietary servers also often implement proprietary protocols, e.g., Exchange ActiveSync.
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 file with a unique name, and each mail folder is a file system directory containing these files. Maildir was designed by Daniel J. Bernstein circa 1995, with a major goal of eliminating the need for program code to handle file locking and unlocking through use of the local filesystem. Maildir design reflects the fact that the only operations valid for an email message is that it be created, deleted or have its status changed in some way.
HCL Notes is a proprietary collaborative software platform for Unix (AIX), IBM i, Windows, Linux, and macOS, sold by HCLTech. The client application is called Notes while the server component is branded HCL Domino.
An online service provider (OSP) can, for example, be an Internet service provider, an email provider, a news provider (press), an entertainment provider, a search engine, an e-commerce site, an online banking site, a health site, an official government site, social media, a wiki, or a Usenet newsgroup.
In computing, text-based user interfaces (TUI), is a retronym describing a type of user interface (UI) common as an early form of human–computer interaction, before the advent of bitmapped displays and modern conventional graphical user interfaces (GUIs). Like modern GUIs, they can use the entire screen area and may accept mouse and other inputs. They may also use color and often structure the display using box-drawing characters such as ┌ and ╣. The modern context of use is usually a terminal emulator.
The term Listserv has been used to refer to electronic mailing list software applications in general, but is more properly applied to a few early instances of such software, which allows a sender to send one email to a list, which then transparently sends it on to the addresses of the subscribers to the list.
Mutt is a text-based email client for Unix-like systems. It was originally written by Michael Elkins in 1995 and released under the GNU General Public License version 2 or any later version.
Opera Mail is the email and news client developed by Opera Software. It was an integrated component within the Opera web browser from version 2 through 12. With the release of Opera 15 in 2013, Opera Mail became a separate product and is no longer bundled with Opera. Opera Mail version 1.0 is available for OS X and Windows. It features rich text support and inline spell checking, spam filtering, a contact manager, and supports POP3 and IMAP, newsgroups, and Atom and RSS feeds.
BlitzMail was an e-mail system used at Dartmouth College in Hanover, New Hampshire, United States. It was one of the earliest e-mail server/client packages. Use of BlitzMail ended in 2011, in favor of a Microsoft suite of email/online collaboration programs, but students still use the term "blitz" rather than "email."
Kontact is a personal information manager and groupware software suite developed by KDE. It supports calendars, contacts, notes, to-do lists, news, and email. It offers a number of inter-changeable graphical UIs all built on top of a common core.
The following tables compare general and technical features of notable email client programs.
HTML email is the use of a subset of HTML to provide formatting and semantic markup capabilities in email that are not available with plain text: Text can be linked without displaying a URL, or breaking long URLs into multiple pieces. Text is wrapped to fit the width of the viewing window, rather than uniformly breaking each line at 78 characters. It allows in-line inclusion of images, tables, as well as diagrams or mathematical formulae as images, which are otherwise difficult to convey.
A console application or command-line program is a computer program designed to be used via a text-only user interface, such as a text terminal, the command-line interface of some operating systems or the text-based interface included with most graphical user interface (GUI) operating systems, such as the Windows Console in Microsoft Windows, the Terminal in macOS, and xterm in Unix.
Minnesota Internet Users Essential Tool (Minuet) is an integrated Internet package for DOS operating systems on IBM-compatible PCs.
GNATS is the GNU project's issue-tracking software.
Alpine is a free software email client developed at the University of Washington.
The following outline is provided as an overview of and topical guide to the Perl programming language:
