Application development

z/OS® Communications Server includes the following enhancements for application, middleware, and workload enablement:
  • Code page enhancements for CSSMTP - z/OS V2R3 Communications Server is enhanced to support multi-byte character sets with the Communications Server SMTP (CSSMTP) application. This enhancement allows migration from SMTPD to CSSMTP for customers that use multi-byte character set code pages, and provides improved code page support for characters in the mail subject line.

    When change was introduced: z/OS V2R3 with the PTF for APAR PI93278

  • CSSMTP customizable ATSIGN character for mail addresses - The Communications Server SMTP (CSSMTP) application is enabled to recognize a different character as the industry standard at sign (@) symbol in a mail address. The specified character is recognized as the at sign symbol only in the SMTP commands and headers in mail messages. This enhancement simplifies migration from SMTPD to CSSMTP for customers that use a code page other than the default IBM-1047 and that have modified mail generation programs to generate mail addresses with an at sign character other than @.

    When change was introduced: z/OS V2R3 and with the PTF for APAR PI52704 for z/OS V2R2

  • Improved CSSMTP code page compatibility with target servers - z/OS V2R3 Communications Server enables the Communications Server SMTP (CSSMTP) application to use a code page other than the standard ISO8859-1 code page to send mail messages to a target server. With this support, CSSMTP can send mail messages with special characters, such as the Euro sign (€), embedded in the body of the mail message in the code page expected by the mail server.
    Restriction: The commands and headers of a mail message are first translated to code page IBM-1047 and then to the code page that is configured for the target server. Characters in the headers might not be translated correctly.

    When change was introduced: z/OS V2R3 and with the PTF for APAR PI73909 for z/OS V2R2

  • Improved CSSMTP TLS compatibility with mail servers - The Communications Server SMTP (CSSMTP) application is enabled to optionally send an EHLO command after a successful TLS negotiation. RFC 3207 (SMTP Service Extension for Secure SMTP over Transport Layer Security) specifies that sending an EHLO command is optional for a SMTP client after a successful TLS negotiation. However, some SMTP servers require an EHLO command after a successful TLS negotiation. To accommodate these servers, a configuration option is provided to enable the sending of an EHLO command after a successful TLS negotiation.

    When change was introduced: z/OS V2R3 and with the PTF for APAR PI56614 for z/OS V2R2.

  • sendmail to CSSMTP bridge - z/OS V2R3 Communications Server removes support for z/OS UNIX sendmail. The z/OS sendmail to CSSMTP bridge (sendmail bridge) is provided to emulate sendmail so that z/OS UNIX users can still use the sendmail command to send the mail message. The sendmail bridge parses input options from the command line, reads the mail message from the UNIX System Services file, and processes the mail message. The input mail message is updated by adding SMTP commands and SMTP headers if there is no header specified in the input mail message. The updated mail message is transmitted to the JES spool data set for the Communications Server SMTP (CSSMTP) application to process.

    When change was introduced: z/OS V2R3 and with the PTF for APAR PI71175 for z/OS V2R2

  • Communications Server support for 8 character TSO User IDs - z/OS V2R3 Communications Server is enhanced to support a maximum TSO/E user ID size of eight characters.

    When change was introduced: z/OS V2R3

  • IPv6 getaddrinfo() API standards compliance - The z/OS Resolver GetAddrInfo API is enhanced. The new enhancement allows the Resolver to return both IPv4 and IPv6 addresses when the following settings are true:
    • AF_UNSPEC is specified for ai_family type.
    • AI_ALL flag is not specified.
    • IPv6 is enabled on the z/OS system.

    When change was introduced: z/OS V2R3

  • CSSMTP migration enablement - A new z/OS Health Checker for z/OS migration health checks to help determine whether you are using any of the following functions on the system:
    • sendmail client
    • sendmail daemon
    • sendmail mail submission agent (sendmail MSA)
    • sendmail mail transfer agent (sendmail MTA)
    • SMPTD daemon
    • SMTPD mail transfer agent (SMPTD MTA)
    Support for these functions is removed in z/OS V2R3.

    When change was introduced: z/OS V2R2. These health checks are removed in z/OS V2R3.

  • CICS transaction tracking support for CICS TCP/IP IBM Listener - The CICS Sockets Listener is enhanced to provide to CICS® the IP addresses and port numbers of the local and remote session partners for use by the CICS Explorer® or Session Monitor.
    Restriction: CICS Transaction Server must be V4R2 or higher.
    Dependency: CICS Transaction Server V4R2 or V5R1 must be active.

    When change was introduced: z/OS V2R2

  • CSSMTP SMTP command editing option - The Communications Server Simple Mail Transfer Protocol (CSSMTP) can be configured to remove the trailing nulls from SMTP Commands (EHLO, HELO, STARTTLS, FROM, RCPT, and DATA).

    When change was introduced: z/OS V2R2

Reference information: See the following topics in z/OS Communications Server: New Function Summary for detailed descriptions that include any applicable restrictions, dependencies, and steps on using the functions:
  • Code page enhancements for CSSMTP
  • CSSMTP customizable ATSIGN character for mail addresses
  • Improved CSSMTP code page compatibility with target servers
  • Improved CSSMTP TLS compatibility with mail servers
  • sendmail to CSSMTP bridge
  • Communications Server support for 8 character TSO User IDs
  • IPv6 getaddrinfo() API standards compliance
  • CSSMTP migration enablement
  • CICS transaction tracking support for CICS TCP/IP IBM Listener
  • CSSMTP SMTP command editing option