Simple Mail Transfer Protocol

About

Simple Mail Transfer Protocol (SMTP) is the protocol almost universally used for handling outgoing email.

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Pages

• /blocking
• SMTP server software includes:
  • Postfix
  • Exim
• Related:
  • email server

Notes

Example session (Wikipedia also has one):

root@cloud1:~# telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 cloud1.vbz.ovh ESMTP Postfix (Ubuntu)
HELO florence
250 cloud1.vbz.ovh
rcpt to:<test@hypertwins.org>
503 5.5.1 Error: need MAIL command
MAIL FROM:<test@oslt.ovh>
250 2.1.0 Ok
RCPT TO:<test@hypertwins.org>
250 2.1.5 Ok
DATA
354 End data with <CR><LF>.<CR><LF>
This is a test message.


.
250 2.0.0 Ok: queued as 48DD8BED39
quit 
221 2.0.0 Bye
Connection closed by foreign host.
root@cloud1:~# 

Links

Reference

• Wikipedia

Testing Tools

• MX Toolbox