SMTP

Stands for “Simple Mail Transfer Protocol.”

SMTP is the protocol used to ship e-mail over the Internet. Email purchasers (like Microsoft Outlook or the macOS Mail app) use SMTP to connect with a mail server and ship e-mail messages. Mail servers additionally use SMTP to alternate messages from one mail server to a different. It will not be used to obtain e-mail messages from a server; as a substitute, the IMAP and POP3 protocols retrieve messages.

An e-mail consumer first establishes an SMTP connection over TCP with the mail server. The consumer then pushes the message to the server, which checks the recipient’s e-mail deal with to see in the event that they’re on the identical domain because the sender; if they’re, it might ship the message. Otherwise, it runs a DNS question to seek out the IP deal with of the recipient’s mail server. The mail server then establishes one other SMTP reference to the vacation spot mail server to ship the message.

When configuring your e-mail consumer, you might be required to specify separate mail servers for incoming and outgoing mail. While some e-mail companies use the identical server for sending and receiving mail (e.g., mail.instance.com), different companies use separate servers for the 2 duties (e.g., imap.instance.com and smtp.instance.com).

NOTE: Modern e-mail purchasers and mail servers use a modified model of SMTP referred to as Extended SMTP, or ESMTP. This up to date model consists of help for e-mail attachments and TLS safety.