Mail delivery is most typically done through one of the SMTP family of protocols, either SMTP or
ESMTP.
What is the ESMTP protocol?
ESMTP (Extended Simple Mail Transfer Protocol) specifies extensions to the original protocol for sending e-mail that supports graphics, audio and video files, and text in different national languages. The original
Internet protocols for sending e-mail are described in Request for Comments (RFC) 822, Standard for the Format of ARPA
Internet Text Messages, and in RFC 821, Simple Mail Transfer Protocol (SMTP). As users demanded to attach various kinds of files to email, the need for additional facilities arose and resulted in RFC 1869, Extended Simple Mail Transfer Protocol. ESMTP provides the facility for a client e-mail program to ask a server e-mail program which facilities it supports and then communicate accordingly.
Answer options A and D are incorrect. IMAPS and POP3S are used for mail pickup.
What is the POP3S protocol?
Post Office Protocol version 3 (POP3) is the protocol that clients use to pick up mail from servers.
Users of POP3 generally store their mail locally on their system and configure their mail client to pick up new mail periodically.
POP3 servers need clients to authenticate with a username and password. This ensures that only authenticated clients can pick up the user's email. Unfortunately, POP3 is an unencrypted protocol, so the username and password travel in cleartext.
POP3S, on the other hand, is POP3 over Secure Sockets Layer. It provides an encrypted connection for the Post Office Protocol. More significantly, it provides an encrypted connection over which the username and password may be transmitted for authentication purposes.
The departmental mail server provides POP3 (internally) and POP3S (internally and externally).
Ultimately, POP3 support will be turned off in favor of IMAPS, which is a more modern protocol that can do everything POP3 can.
