SMTP

Summary and Commands

Simple Mail Transfer Protocol rfc5321 Message Submission for Mail rfc6409

Outgoing email (SMTP) uses port 25

Command	Comment
ATRN	Authenticated TURN
AUTH	Authentication
BDAT	Binary data
BURL	Remote content
DATA	The actual email message to be sent. This command is terminated with a line that contains only a
EHLO	Extended HELO
ETRN	Extended turn
EXPN	Expand
HELO	Identify yourself to the SMTP server.
HELP	Show available commands
MAIL	Send mail from email account
MAIL	FROM: me@mydomain.com
NOOP	No-op. Keeps you connection open.
ONEX	One message transaction only
QUIT	End session
RCPT	Send email to recipient
RCPT	TO: you@yourdomain.com
RSET	Reset
SAML	Send and mail
SEND	Send
SOML	Send or mail
STARTTLS
SUBMITTER	SMTP responsible submitter
TURN	Turn
VERB	Verbose
VRFY	Verify

Example

telnet 10.10.45.250 25
#Trying 10.10.45.250...
#Connected to MACHINE_IP.
#Escape character is '^]'.
#220 bento.localdomain ESMTP Postfix (Ubuntu)

helo telnet
#250 bento.localdomain

mail from: 
#250 2.1.0 Ok

rcpt to: 
#250 2.1.5 Ok

data
#354 End data with .

subject: Sending email with Telnet
Hello Frank,
I am just writing to say hi!             
.
#250 2.0.0 Ok: queued as C3E7F45F06

quit
#221 2.0.0 Bye
#Connection closed by foreign host.