An e-mail client, also called a mail user agent (MUA), is a computer program that is used to read and send e-mail.

...[M]ost modern MUAs have to support protocols like POP3 and Internet Message Access Protocol (IMAP) to communicate with a remote MTA located at the e-mail providers machine.

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 Simple Mail Transfer Protocol (SMTP) is used by most e-mail clients to send e-mail.

In addition to the fat client e-mail clients, or small MUAs in cooperation with a local MDA/MTA, presented here, there are also Web-based e-mail programs called webmail.

     source - E-mail client. (2006, August 5). In Wikipedia, The Free Encyclopedia. Retrieved September 3, 2006, from http://en.wikipedia.org/wiki/Email_client

Hautspot fully supports all modern e-mail clients (utilizing POP3, IMAP4, and SMTP) running on platforms which support them, including Outlook, SeaMonkey MailNews, Netscape Messenger, GroupWise, Eudora, Kmail, and more, on Microsoft Windows, IBM OS/2, Serenity Systems eComStation, Linux, Mac OS X, BeOS, Irix, HP-UX, IBM AIX, Sun Solaris, and more. Of course, webmail is fully supported when running over standard TCP ports in a supported web browser.

It is important to remember that POP3, IMAP4, and SMTP all communicate natively unencrypted over well-known ports and are inherently insecure. Recent developments in security have added the ability to encrypt such transmissions using TLS (Transport Layer Security) over the same standard ports. Hautspot recommends the use of TLS (when supported by the client's mail service provider) for added security.

Outlook, SeaMonkey MailNews, Netscape Messenger, GroupWise, Eudora, Kmail, Windows, OS/2, eComStation, Linux, Mac OS X, BeOS, Irix, HP-UX, IBM AIX, and Sun Solaris are trademarks of their respective owners.