Проверка SMTP с помощью Telnet / How to test SMTP operations using Telnet

telnet localhost 25
ehlo domain name
mail from: <email address>
rcpt to: <email address>

DATA
From:"test" <aemail address>
To:"test end"<email address>
Subject: the test message

This is test text on test page.

<enter>
<enter>
.
<enter>

quit