Email related terminology Basic email terminology list.

DNS
The Domain Name System (DNS) is a distributed Internet directory service. DNS is used primarily to translate between domain names and IP addresses, and to control Internet e-mail delivery. A domain name is a meaningful and easy-to-remember "handle" for an Internet address.

Dynamic IP address
Most ISPs assign their customers a dynamic IP address. This means the customer´s equipment will most likely be assigned a different IP address each time a connection is established.

ESMTP
In extension to the SMTP service which defines a means whereby a server SMTP can inform a client SMTP as to the service extensions it supports. The details of ESMTP are in RFC 1869.

ETRN "Extended TURN" An ESMTP command with which a client asks the server to deliver queued mail to the client via a new ESMTP connection.

SMTP
(Simple Mail Transfer Protocol) SMTP is a TCP/IP protocol governing electronic mail transmission and reception. The details of SMTP are in RFC 821 of the Internet Engineering Task Force (IETF).

TCP/IP
(Transmission Control Protocol/Internet Protocol) TCP/IP is the basic communication language or protocol of the Internet.