What Is SMTP (Simple Mail Transfer Protocol)? Can I use it to send emails?

SMTP (Simple Mail Transfer Protocol) is network protocol to be used to transfer RFC822-style messages between different mail hosts as well as to submit new messages to a host for delivery. SMTP is in very wide use since 1982.

Yes, you can use SMTP to send out an email message through your email provider servers, like Gmail, Yahoo, or your office email servers. SMTP can not be used to download email messages from a remote email server.

IMAP is defined by "RFC 821 - SIMPLE MAIL TRANSFER PROTOCOL" in 1982 as below:

The objective of Simple Mail Transfer Protocol (SMTP) is to transfer mail reliably and efficiently.

SMTP is independent of the particular transmission subsystem and requires only a reliable ordered data stream channel, like TCP, NCP, NITS or X.25.

An important feature of SMTP is its capability to relay mail across transport service environments. A transport service provides an interprocess communication environment (IPCE). An IPCE may cover one network, several networks, or a subset of a network. It is important to realize that transport systems (or IPCEs) are not one-to-one with networks. A process can communicate directly with another process through any mutually known IPCE. Mail is an application or use of interprocess communication. Mail can be communicated between processes in different IPCEs by relaying through a process connected to two (or more) IPCEs. More specifically, mail can be relayed between hosts on different transport systems by a host on both transport systems.

⇒ What Is IMAP (Internet Message Access Protocol)

⇐ What Is the JavaMail API

⇑ Download and Install JavaMail Library

⇑⇑ FAQ for JavaMail