This FAQ is designed to answer common questions about sending e-mail from MVS.
What are my options for sending e-mail from MVS?
What is SMTP? What is its purpose?
What is RFC822?
What is MIME and why is it important?
What does a SMTP data stream consist of?
What does a SMTP data stream consist of?
The SMTP data stream consists of a series of RFC821 statements identifying the start of the SMTP conversation and the sender and recipients, followed by the message data. The message data usually includes a series of RFC822 message headers that describe the message to the receiving e-mail client. The actual message text follows the message headers.
A simple annotated example is below:

HELO BAR.COM

HELO command is used to identify the sender-SMTP to the receiver-SMTP. In the above, BAR.COM is the domain name of the sending SMTP user. The HELO command begins the SMTP conversation.
               
MAIL FROM:<foo@bar.com>

MAIL command tells the SMTP-receiver that a new mail transaction is starting. it gives the <reverse path> which
contains the source mailbox and can be used to report errors. The 1st host in the <reverse path> should be the host sending the MAIL command ,in this case is foo@bar.com.
                                 
RCPT TO:<wayne@bar.com>

RCPT is the 2nd step in the procedure. It identifies one recepient, specifying the destination mailbox. If accepted, the receiver-SMTP returns a 250 OK reply and stores the destination mailbox, in this case <jones@bar.com>, as the host receiving this command.
                                       
DATA  

DATA command is the 3rd step in the SMTP procedure. If accepted, the receiver-SMTP returns a 354 intermediate reply and considers all succeeding lines to be message text. The mail data includes the memo header items such at DATE, Subject, TO, CC and From. The format of the memo headers is specified by RFC822. The following is all considered mail data;
Date: Fri, Jul 16 1999, 13:41:30 -0400                                  
From: "Commissioner Gordon" <foo@bar.com>                        
Subject: DAILY REPORT OF DISK UTILIZATION                              
To: "Bruce Wayne" <wayne@bar.com>                              
                                                                       
                                                                       
    Please fix the bulb in the searchlight    

The actual message data follows the RFC822 message headers, in this case following the 'blank' line after the To: "Bruce Wayne" <wayne@bar.com> line.
                                                                           
. 
A single period marks the end of the current message text. The receiver-SMTP will expect either another HELO command to begin a new conversion or QUIT to end the SMTP datastream
                                                                         
QUIT
Ends the conversation and specifies the receiver must close the transmission channel