What Is An SMTP Server?

Simple Mail Transfer Protocol (SMTP) is a standard computer network protocol for handling outgoing emails. An SMTP server is simply any computer designated to handle requests from email clients for sending messages via this protocol.

To use an SMTP server, an email client must be configured with the server's name or address. Typical SMTP server names are smtp.comcast.net or mail.btinternet.com. Internet Service Providers (ISPs) normally maintain SMTP servers for their customers to use. Alternatively, servers from Web-based email providers such as Google (smtp.gmail.com) are attached to those services and sometimes (as in Google's case) open to any Internet client. Corporations also set up similar servers for their own internal (intranet) email.

→ See also - Top Free POP3 and IMAP Email Services
→ See also - How Internet Email Works (email.about.com)