The application layer process that sends mail uses __________. When a client sends email, the client process connects with a ser
ver process on well-known port __________. A client retrieves email, however, using one of two application layer protocols: ________ or ________. With ________, mail is downloaded from the server to the client and then deleted on the server. The server starts the __________ service by passively listening on TCP port __________ for client connection requests. However, when a client connects to ta server running __________, copies of the messages are downloaded to the client applications. The original messages are kept on the server until they are manually deleted.
The application layer process that sends mail uses Simple Mail Transfer Protocol (SMTP). When a client sends email, the client process connects with a server process on well-known port 25. A client retrieves email, however, using one of two application layer protocols: Post Office Protocol (POP) or Internet Message Access Protocol (IMAP). With POP, mail is downloaded from the server to the client and then deleted on the server. The server starts the POP service by passively listening on TCP port 110 for client connection requests. However, when a client connects to a server running IMAP, copies of the messages are downloaded to the client applications. The original messages are kept on the server until they are manually deleted.
