IMAP4 is an especially convenient method of delivery for those who use multiple computers and would like to use an email client instead of Webmail. A growing number of email users have one machine at work and a different one at home, possibly also a laptop for travel, or they use public PCs in a library or computer lab. Like POP3, mail is delivered to a central server, but the mail client (Eudora, Outlook, Netscape Messenger) does not copy it all at once and then delete it from the server. It's more of an interactive model, where the user can ask to view all messages or messages meeting certain criteria. Messages on the central server can be marked with various status flags (e.g. "deleted" or "answered"), moved to folders either on a local computer or on the server, and they stay on the server until explicitly removed by the user. This way the messages can be viewed from other computers until they are marked for deletion or downloaded to a folder on a computer. In short: IMAP4 is designed to permit manipulation of remote mailboxes as if they were on a local machine.

POP3 is designed to support "offline" mail processing. POP3 differs from IMAP4 as it 'downloads' the email messages through an email client (Eudora, Outlook, Netscape Messenger, etc.) One of the chief virtues of offline access is that it less dependent on server resources (meaning less time needed to stay connected to the internet.) However, email access for the mobile user is limited.

Users who need to check their email from various locations should consider using Webmail or IMAP. Most of our clients prefer Webmail due to its ease of use and the fact that it can be accessed with just a web browser.