Apple Mac OS X Server Version 10.4 or Later Manual do Utilizador descarregar pdf (Página 17)

Chapter 1 Mail Service Setup 17

Post Office Protocol (POP)

POP is used only for receiving mail, not for sending mail. The mail service of Mac OS X

Server stores incoming POP mail until users have their computers connect to the mail

service and download their waiting mail. After a user’s computer downloads POP mail,

the mail is stored only on the user’s computer. The user’s computer disconnects from

the mail service, and the user can read, organize, and reply to the received POP mail.

The POP service is like a post office, storing mail and delivering it to a specific address.

An advantage of using POP is that your server doesn’t need to store mail that users

have downloaded. Therefore, your server doesn’t need as much storage space as it

would using the IMAP protocol. However, because the mail is removed from the server,

if any client computers sustain hard disk damage and lose their mail files, there’s no

way to recover these files without using data backups.

Another advantage of POP is that POP connections are transitory. Once the mail is

transferred, the connection is dropped and the load on both the network and the mail

server is removed.

POP isn’t the best choice for users who access mail from more than one computer, such

as a home computer, an office computer, and a laptop while on the road. When a user

fetches mail via POP, the mail is downloaded to the user’s computer and is usually

completely removed from the server. If the user logs in later from a different computer,

the user won’t be able to see previously downloaded mail.

Internet Message Access Protocol (IMAP)

IMAP is the solution for people who need to use more than one computer to receive

mail. IMAP is a client-server mail protocol that allows users to access their mail from

anywhere on the Internet. Users can send and read mail with a number of IMAP-

compliant email clients.

With IMAP, a user’s mail is delivered to the server and stored in a remote mailbox on

the server; to users, mail appears as if it were on the local computer. A key difference

between IMAP and POP is that with IMAP the mail isn’t removed from the server until

the user deletes it.

The IMAP user’s computer can ask the server for message headers, ask for the bodies of

specified messages, or search for messages that meet certain criteria. These messages

are downloaded as the user opens them. IMAP connections are persistent and remain

open, maintaining load on the server and possibly the network as well.

1 2 ... 12 13 14 15 16 17 18 19 20 21 22 ... 112 113

Sem comentários

Apple Mac OS X Server Version 10.4 or Later Manual do Utilizador Página 17