SMTP commands

The following are general SMTP commands and data rules for CSSMTP:

Rules:
  • The following size limits apply:
    • The SMTP command lines must not exceed 510 characters in length
    • Data lines must not exceed 998 characters in length
    • Path addresses must not exceed 255 characters in length
    • Domain names must not exceed 255 characters in length
    • User names, which are the local part of a mailbox specification, must not exceed 64 characters in length
    • Maximum number of RCPT records per mail message is 2000
  • Files must not contain graphic characters (0x00 through 0x3f) except for the tab character (0x09) or newline character (0x15).
Tips:
Result: Trailing blanks are removed from all records.
Table 1. SMTP commands that are supported by CSSMTP
Subcommand Supported by SMTP Server Supported by CSSMTP application Description Reference
DATA YES YES Defines information as the data text of the mail body. DATA command: Define the following information as data
EHLO NO YES Identifies the domain name of the sending host to SMTP. EHLO command: Identify the domain name of the sending host to SMTP
EXPN YES NO Verifies whether a mailbox exists on the local host. Command is not implemented
HELO YES YES Identifies the domain name of the sending host to SMTP. HELO command: Identify the domain name of the sending host to SMTP
HELP YES NO Provides help with SMTP commands. Command is not implemented
MAIL FROM YES YES Specifies the mail sender. MAIL FROM command: Specify the sender of the mail
NOOP YES NO Returns a 250 OK return code when SMTP is responding. Command is not implemented
QUEU YES NO Gets information about mail that is queued at SMTP for delivery. Command is not implemented
QUIT YES YES Stops SMTP processing. QUIT command: End SMTP processing
RCPT TO YES YES Specifies the mail recipients. RCPT TO command: Specify the recipients of the mail
RSET YES YES Resets the SMTP processing to the initial state. RSET command: Reset the SMTP processing to the initial state
STARTTLS NO YES Tells the CSSMTP application that the SMTP server is currently able to negotiate the use of TLS. STARTTLS command: Indicate the ability to negotiate the use of TLS
TICK YES NO Inserts an identifier into the batch SMTP response data set. Command is not implemented
VERB YES NO Enables or disables verbose mode.
Note: VERB ON can cause spool problems for SMTP if the REPLY TO: user is not a valid NJE node.user.
Command is not implemented
VRFY YES NO Verifies whether a mailbox exists on the local host. Command is not implemented
Note: The EXPN, HELP, NOOP, QUEU, TICK, VERB, and VRFY commands and the optional commands SAML, SEND, SOML, and TURN (see RFC 821 for details), are not implemented in the CSSMTP application. These commands are ignored and are not processed.

Data sets that contain SMTP commands can be written to the JES spool data set as SYSOUT data sets. These SYSOUT data sets contain either punch or NETDATA records. Data sets originate from users on the same system as the CSSMTP address space or from users on any system that is connected to the host system through an NJE network.