THE VIRTUAL SERVER HANDBOOK

Protocols

SMTP (Simple Mail Transfer Protocol) enables computers to send mail

to each other using the Internet. SMTP pertains only to the protocol used by

computers to transfer and deliver E mail.

POP (Post Office Protocol) enables mail recipients to retrieve mail that has

arrived.

IMAP (Internet Message Access Protocol) enables message retrieval and

storage.

SMTP server

An SMTP server must have the following to send and receive E mail across

the Internet:

An SMTP server should have a continuous Internet connection and be

prepared to receive mail at all times because incoming mail can arrive

at any time of day.

An SMTP server is also asked to deliver outgoing messages on behalf

of a computer that does not have complete SMTP capabilities.

An SMTP server performs relays in behalf of other computers. When an

SMTP server is asked to deliver a message in behalf of another

computer and the recipient of the message is not a local user on the

system, the SMTP server is asked to relay the message to the eventual

destination server.

POP server

A POP server enables recipients of E mail messages to retrieve the

messages from the POP server. Once the messages are retrieved by

recipients, the messages cannot be "put back" or stored on the server.

IMAP server

An IMAP server enables users to retrieve mail and store mail (unlike a POP

server). Users can shuffle messages to and from the IMAP server.

COPYRIGHT 

 1999  DIGITAL TOOLS  LLC.

63