Sending email using raw SMTP commands
You can send email(s) by connecting to your SMTP server, and using raw SMTP commands.
E.g. assume your SMTP is localhost, listening port 25, enter the commands in bold
# telnet localhost 25
Connected to localhost.localdomain.
Escape character is '^]'.
220 smtp.example.com ESMTP Postfix (Ubuntu)
mail from: email@example.com
250 2.1.0 Ok
rcpt to: firstname.lastname@example.org
250 2.1.5 Ok
354 End data with
This is a test mail
250 2.0.0 Ok: queued as BA2FD1DB96
221 2.0.0 Bye
Connection closed by foreign host.