GroupOffice is a groupware suite that takes your office online, implementing online collaboration and CRM. It allows you to share projects, calendars, files and email online with co-workers and clients. It is easy to use and fully customizable. It also features synchronization with PDAs and Outlook.
The SeaMonkey project is a community effort to develop an all-in-one Internet application suite. It contains an Internet browser, email and newsgroup client with an included Web feed reader, HTML editor, IRC chat, and Web development tools, and is sure to appeal to advanced users, Web developers, and corporate users. It uses much of the Mozilla source code powering such successful siblings as Firefox, Thunderbird, Camino, Sunbird, and Miro.
Thunderbird is a total redesign of the Mozilla mail component to produce a cross-platform, stand-alone mail application using the XUL user interface language. It has many new features, among them the ability to customize your toolbars the way you want them. a new look and feel with a large number of downloadable themes which alter the appearance of the client, and the ability to add UI extensions.
Cerb is a fast and flexible Web-based platform for business collaboration and automation. It helps you remember anything about anyone, collaborate from anywhere, deftly reply to a flood of email, automate, stay informed, capture feedback, track time, flag opportunities, manage tasks, share expert knowledge, and otherwise execute efficiently.
Open-Xchange Server Edition is a multi-tier, small footprint solution that integrates seamlessly into customer’s architectures, enabling smooth start of operation based on services. The Open-Xchange Server Edition supports different Enterprise Linux systems like SUSE Linux Enterprise Server 10, Red Hat Enterprise Linux 5, and Debian Etch. Users are presented with a highly advanced, improved, and intuitive browser based interface that meets all their email, calendaring, tasking, contacts, and document storage requirements. Further integrations like LDAP-support or ADS are possible. It's designed for medium organizations and educational and public administrations that want to have a customizable communication solution.
EGroupware is a Web-based groupware suite. It contains many modules, including Calendar (personal calendar and group scheduling, notifications and alarms), Mail (IMAP only), InfoLog (todos, notes, and phone calls linked to contacts/CRM), Contacts (an address book for storing and sharing contact information), ProjectManager, Tracker (bug or incident tracking), TimeSheet, SyncML, CalDAV & CardDAV support, and SiteMgr content management
This is a PHP class that attempts to validate a given e-mail address at four levels: matching the address against a RFC compliant regular expression; checking whitelists and blacklists of domains with typing mistakes, disposable email addresses, and temporary and fake domains; verifying the existence of the destination SMTP server by verifying the respective DNS MX record; and connecting to that server to see if the given address is accepted as a valid recipient. The class also features a debugging output option that lets you see the remote SMTP server connection and data exchange dialog to see the real cause why an apparently valid address may not be accepting messages.
SquirrelMail is a standards-based Webmail package. It includes built-in pure PHP support for the IMAP and SMTP protocols, and all pages are rendered in pure HTML 4.0 for maximum compatibility across browsers. It has very few requirements, and is very easy to configure and install. It has all the functionality you would want from an email client, including strong MIME support, address books, and folder manipulation.
Roundcube Webmail is a browser-based, multilingual IMAP client with an application-like user interface. It provides the full functionality you expect from an email client, including MIME support, address book, and folder manipulation. High extensibility is granted by the plugin API and the user interface is fully skinnable using XHTML and CSS 2.