SMTP conversation

article #133, updated 24 days ago

A sample SMTP conversation.  Blue is transmit, red is receive; all exists within a command-prompt window.  The messages received will vary somewhat, but the initial numbers won’t.  The greater-than and less-than signs (< >) are required. The below works fine in Cygwin with ‘inetutils’ installed (which includes ‘telnet’), or in CMD with the Windows ‘telnet’ installed. Linuxes obviously have various telnets! ‘putty’ on Windows will do it also, in telnet mode, port 25, just replace the first line with GUI putty setup.

telnet mail.srcdomain.com 25

220 mail.destdomain.com ESMTP

HELO test.srcdomain.com

250 mail.destdomain.com

MAIL FROM: <email@srcdomain.com>

250 2.1.0 Sender OK

RCPT TO: <email@destdomain.com>

250 2.1.5 Ok

DATA

354 Enter mail, end with “.” on a line by itself

testing
testing
testing
.

250 2.0.0 Ok: queued as xxxxxxx

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