Gmail is a free, advertising-supported email service provided by Google. Users may access Gmail as secure webmail, as well via POP3 or IMAP protocols. The Gmail service currently provides more than 7 GB of free storage per account. Users can rent additional storage (shared between Picasa Web Albums, Google Docs and Gmail) from 20 GB to 16 TB. Gmail's spam filtering features a community-driven system: when any user marks an email as spam, this provides information to help the system identify similar future messages for all Gmail users.
Microsoft Exchange Server is the server side of a client–server, collaborative application product developed by Microsoft. Exchange's major features consist of electronic mail, calendaring, contacts and tasks; support for mobile and web-based access to information; and support for data storage.
Microsoft Outlook is a personal information manager from Microsoft. It can be used as a stand-alone application, or can work with Microsoft Exchange Server and Microsoft SharePoint Server for multiple users in an organization, such as shared mailboxes and calendars, Exchange public folders, SharePoint lists and meeting schedules.
Lotus Notes is the client of a collaborative platform. It's an integrated desktop client option for accessing business e-mail, calendars and applications on IBM Lotus Domino server.
Zoho Mail is an email hosting service built with the needs of a modern business in mind. It provides best-in-class features exceeding even those of desktop emailing software for business users to communicate effectively while catering to the fine-grained customization and mailbox management needs of IT administrators. Additionally the seamless contextual integration with 20+ other Zoho applications provides higher productivity & collaboration.
Kerio Connect is a commercial mail and groupware server developed by Kerio Technologies. It runs on Windows, Linux, and Mac OS X. Its features include encrypted access using SSL, anti-virus and anti-spam protection, native over-the-air handheld synchronization, webmail interface, connector for Microsoft Outlook and groupware features.
LotusLive iNotes is a security-rich, Web-based e-mail service that provides essential messaging and calendaring capabilities to businesses of all sizes.
Rackspace Email hosting gives you the power to securely manage email
from any web browser on the device of your choice - no licenses to keep
track of or software to download. Microsoft Outlook compatible
Support your company’s success with an email solution that means business. Get all the features and security of a premium desktop solution—with the flexibility and low cost of a web application. WebEx Mail includes world-class antivirus and spam guard, live search, generous storage, right-click menus and more. It’s easy to set up, use, manage and grow. Integrate WebEx Mail instantly and seamlessly with Webex WebOffice.