KMail allows you to access your electronic mail in various ways. The access type largely depends on your Internet Service Provider (ISP) or mail server. The main access types are POP3 and IMAP.
POP3 is a standardized procedure for receiving e-mail. A POP3 server stores the messages until the user retrieves them with a POP3 client (in this case, KMail). This method is used frequently by Internet Service Providers (ISPs).
With IMAP, e-mail messages can be received and administered on the server without downloading them to the hard disk. This is often used in internal networks as it allows access to mail from different computers.