SMTP and Relay SMTP

SMTP is a Simple Mail Transfer Protocol which is an Internet standard for emailing process over the internet. SMTP is specified for outgoing mail server and a TCP port is assigned to it. Mostly all electronic mail servers and other mail transfer agents use SMTP to send and receive mail messages whereas user-level client mail applications use SMTP for sending messages to a mail server and for receiving messages, client applications use either the POP or the IMAP to access their mail box accounts on a mail server. SMTP is a simple, text-based protocol, in which a sender communicates with recipient using a TCP connection and was designed as an electronic mail transport and delivery protocol. Since SMTP is a delivery protocol only, It cannot pull messages from a remote server. However, the SMTP protocol has a feature to initiate mail queue processing on a remote server so that the requesting system may receive any messages destined for it. An e-mail client/application needs the name or the IP address of an SMTP server as part of its configuration. The server will deliver messages on behalf of the user. End users connected to the Internet can use the services of an e-mail provider that is not necessarily the same as their connection provider (ISP). Some Internet service providers intercept the TCP port 25, which restricts their users to send the mails via a relaying SMTP server outside the ISP's network and thus they are able to use only the SMTP server of the service provider(ISP) only. There are some SMTP servers that support ports other than the TCP port 25, using which the user can connect to those SMTP servers even when their TCP port 25 is blocked. It is practically useful to the mobile users, who connects to different ISP. They can connect to these mobile SMTP servers instead of frequently changing their server setting to connect to the SMTP pf the ISP service they are using. These mobile SMTP server or the relaying SMTP server allows the SMTP client settings to be used unchanged worldwide irrespective of the ISP they connect with. Mobile SMTP helps users in many ways, users can use the sane email address anywhere and the same email programs. It helps reduce the server delays, increasing the speed and privacy and avoid blacklisting. Using a relay SMTP or the mobile SMTP is quite easy as well, one can simply download and install your own SMTP server or a user can also use a SMTP relay service.