SMTP: (pronounced as separate letters) short for Simple Mail Transfer Protocol, a protocol for sending e-mail messages between servers. Most e-mail systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP. In addition, SMTP is generally used to send messages from a mail client to a mail server. This is why you need to specify both the POP or IMAP server and the SMTP server when you configure your e-mail application.
What does SMTP mean to you?
You would probably most likely encounter it when setting up your hosted email on your local email client (such as Outlook or Eudora).
SMTP is also referred to as “outgoing email” by most of the email programs (clients). If you host your own domain and email service, and need to know what your specific SMTP is, you must ask your hosting service provider.
If you use public email services, such as Yahoo, there is no need for you to know your SMTP .
Sometimes you need to ask your ISP (internet service provider) for SMTP information – for example, if you use AT&T, or for your mobile phone service, or Optimum Online for your home internet connection, you may have to confirm your SMTP (outgoing) settings with them, first.