Title: smtp_telnet_session
Subject: useful for debug email servers

telnet mail.domain.ext 25
HELO local.domain.name - dont worry too much about your local domain name although you really should use your exact fully qualified domain name as seen by the outside world the mail 
MAIL FROM: mail@domain.ext
RCPT TO: mail@otherdomain.ext
DATA
Subject:-type subject here
type message
.
quit
----------------------------
Debian:
exim4 -bh 127.0.0.1  cat <<EOF
HELO example.com
MAIL FROM: <john@stilen.com>
RCPT TO: <john@stilen.com>
DATA
Subject: something
your message here
.
QUIT
EOF