The Lightweight Directory Access Protocol is an open, vendor-neutral, industry standard application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network. Directory services play an important role in developing intranet and Internet applications by allowing the sharing of information about users, systems, networks, services, and applications throughout the network. As examples, directory services may provide any organized set of records, often with a hierarchical structure, such as a corporate email directory. Similarly, a telephone directory is a list of subscribers with an address and a phone number.
MySQL is an open-source relational database management system (RDBMS). Its name is a combination of "My", the name of co-founder Michael Widenius's daughter My, and "SQL", the acronym for Structured Query Language. A relational database organizes data into one or more data tables in which data may be related to each other; these relations help structure the data. SQL is a language that programmers use to create, modify and extract data from the relational database, as well as control user access to the database. In addition to relational databases and SQL, an RDBMS like MySQL works with an operating system to implement a relational database in a computer's storage system, manages users, allows for network access and facilitates testing database integrity and creation of backups.
PostgreSQL, also known as Postgres, is a free and open-source relational database management system (RDBMS) emphasizing extensibility and SQL compliance. It was originally named POSTGRES, referring to its origins as a successor to the Ingres database developed at the University of California, Berkeley. In 1996, the project was renamed to PostgreSQL to reflect its support for SQL. After a review in 2007, the development team decided to keep the name PostgreSQL and the alias Postgres.
An email client, email reader or, more formally, message user agent (MUA) or mail user agent is a computer program used to access and manage a user's email.
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).
The Cyrus IMAP server is electronic mail server software developed by Carnegie Mellon University. It differs from other Internet Message Access Protocol (IMAP) server implementations in that it is generally intended to be run on sealed servers, where normal users cannot log in.
The following tables compare general and technical features of notable email client programs.
Dovecot is an open-source IMAP and POP3 server for Unix-like operating systems, written primarily with security in mind. Timo Sirainen originated Dovecot and first released it in July 2002. Dovecot developers primarily aim to produce a lightweight, fast and easy-to-set-up open-source email server.
Sieve is a programming language that can be used for email filtering. It owes its creation to the CMU Cyrus Project, creators of Cyrus IMAP server.
Roundcube is a web-based IMAP email client. Roundcube's most prominent feature is the pervasive use of Ajax technology. Roundcube is free and open-source software subject to the terms of the GNU General Public License (GPL-3.0-or-later), with exceptions for skins and plugins.
The comparison of mail servers covers mail transfer agents (MTAs), mail delivery agents, and other computer software that provide e-mail services.
mysqlBind/unxsBind is a DNS management software system. It supports Internet Systems Consortium BIND Domain Name System (DNS) and is distributed as open source software under the GNU General Public License.
CrushFTP is a proprietary multi-protocol, multi-platform file transfer server originally developed in 1999. CrushFTP is shareware with a tiered pricing model. It is targeted at home users on up to enterprise users.
hMailServer was a free email server for Windows created by Martin Knafve. It ran as a Windows service and includes administration tools for management and backup. It had support for IMAP, POP3, and SMTP email protocols. It could use external database engines such as MySQL, MS SQL or PostgreSQL, or an internal MS SQL Compact Edition engine to store configuration and index data. The actual email messages were stored on disk in a raw MIME format. As of January 15th, 2022, active support and development were officially halted, although version 5.6 will continue to receive updates for critical bugs.
EGroupware is free open-source groupware software intended for businesses from small to enterprises. Its primary functions allow users to manage contacts, appointments, projects and to-do lists. The project releases its software under the terms of GNU General Public License (GPL).
Zarafa was an open-source groupware application that originated in the city of Delft in the Netherlands. The company that developed Zarafa, previously known as Connectux, is also called Zarafa. The Zarafa groupware provided email storage on the server side and offered its own Ajax-based mail client called WebAccess and a HTML5-based, WebApp. Advanced features were available in commercially supported versions. Zarafa has been superseded by Kopano.
Discourse is an open source Internet forum system. Features include threading, categorization and tagging of discussions, configurable access control, live updates, expanding link previews, infinite scrolling, and real-time notifications. It is customizable via its plugin architecture and its theming system.
