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 SMTP? What is its purpose?
SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used in sending and receiving mail. It is Internet's standard host to host mail transport protocol. It is defined by RFC821. Request For Comments (or RFC) documents are the written definitions of the protocols and policies of the Internet.

What is RFC822?
What is RFC822?
RFC822 is the standard for Internet Text messages. This standard specifies the syntax for text messages that are sent among computer users within the framework of "electonic mail" . RFC822 has been updated by RFC1123, RFC1138, RFC1148, RFC1327, RFC2156

What is MIME and why is it important?
What is MIME and why is it important?
MIME is short for Multipurpose Internet Mail Extensions. MIME is defined and extended by many different RFCs. (List of MIME RFCs) MIME allows the sending of binary and other complex messages such as HTML through the text based protocols of SMTP. Without MIME, the sending of attachments or in-line HTML would be impossible.
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 2010, 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

1. Copy your TCP/IP profile data set (DDname SYSTCPD in the SMTP started task) to a new data set.
2. In your SMTP CONFIG data (DDname CONFIG in the SMTP started task) specify a IPMAILERADDRESS statement. The syntax is IPMAILERADDRESS xx.xx.xx.xx where the xx.xx.xx.xx is the numeric IP address of the target SMTP mail server.
3. Comment out the NSINTERADDR statements in the copied SYSTCPD data set. This will prevent the SMTP server from using Domain Name Services to resolve the location of any e-mail address. SMTP will now only use the site table to resolve e-mail addresses into target host IP addresses.
4. Change your SMTP started task JCL to use the altered copy of the TCP/IP parameters and the updated CONFIG data set .Restart your SMTP server. Any mail for which the IP address of the target host cannot be determined will now be redirected to the SMTP server named in the IPMAILERADDRESS statement.
5. Or you can use SMTP-Send's Spool Server and skip steps 1 through 4.

• Don't connect directly to the Internet. A firewall can be used to block any unwanted traffic. If you don't use your SMTP server to receive external e-mail, ask your firewall people to disable port 25 to inbound traffic. That way spammers can't send any inbound relay traffic.
• Relay all of your e-mail to another non-MVS SMTP server that can detect the unwanted relay traffic.
• If you send all of your e-mail throught the Spool/NJE interface you can set MAXMAILBYTES 1 which means you only accept 1 byte messages over TCP connections
• You can code the SMTPEXIT to inspect all traffic coming into your SMTP Server via TCP/IP. With the addtion of APAR PQ13476 you can also inspect data entering via the JES Spool. Refer to Communications Server IP Configuration Reference for additional information on SMTP Exits.
• Use SMTP-Send's Spool Server instead of IBM's SMTP Server to only accept SMTP traffic from the spool.