SMTPPLUS is a product designed to provide a replacement for the VM SMTP machine included as part of TCP/IP. In addition to performing the functions of VM SMTP, it offers higher performance, as well as integrated spam and virus scanning.

SMTPPLUS acts as an SMTP transport, listening for SMTP mail on TCP port 25, and delivering that mail either over TCP/IP to other hosts, or directly to the virtual reader of a VM user. SMTPPLUS is also capable of performing virus and spam scanning, and performing policy-based routing or rejection of messages determined to be spam or to contain viruses, supporting authenticated delivery, header rewriting, and full IPv6 support.


Target Audience for SMTPPLUS

SMTPPLUS meets the needs of users who:

  • Need to deliver SMTP-based electronic mail to and from z/VM systems
  • Need to support users and system applications using MAILBOOK or other MUAs to transmit MIME-encoded files
  • Need to support mailing list servers like L-Soft's LISTSERV or other bulk list management software using z/VM




SMTPPLUS has two major components : a core message-processing system implemented as a Linux virtual appliance, and a CMS-based application proxy engine which uses the VM TCP/IP stack to manage interaction with the core message processor.


Highlights of the new functions available with SMTPPLUS are:

  • High-Performance Mail Processing

    SMTPPLUS uses the powerful and popular Exim MTA as the core of its Mail Transfer Agent. Exim is extremely customizable and is in wide use at installations of all sizes. Exim is especially popular at sites with very high mail volumes.
  • Automated Virus Scanning

    SMTPPLUS uses the Amavis-NG framework as the infrastructure for both its spam and its virus detection. Mail is passed to Amavis, which in turn feeds it through a set of filters to determine the ultimate fate of both incoming and outgoing messages.  The default configuration uses the Clam AV antivirus scanner; however, SMTPPLUS is easily configured to use other scanners, as each site prefers.
  • Automated Spam Detection, Tagging and Rejection

    SMTPPLUS employs the popular SpamAssassin spam scanner. The default configuration takes a fairly conservative view of what it considers spam;  messages deemed to be spam, but not so offensively so as to be discarded unread, are tagged as spam before delivery, and thus can be easily filtered by the end- user's mail tool. SMTPPLUS is configured to allow Bayesian learning capabilities, but it is the responsibility of the site administrator to sort through the spam and ham folders and recategorize anything misclassefied, so that the Bayes algorithms actually learn to discriminate better.
  • Automated Removal of Hostile Payloads

    The SMTPPLUS virus scanner will quarantine any message it recognizes as infected, for further perusal by the system administrator. The quarantine code can be configured to simply discard the message, to remove the infected content (if possible), and optionally to warn either the sender or the recipient that the message was infected. It will also scan for, and remove, message parts with specified extensions (e.g. .exe and .com).
  • Compatibility with VM SMTP Spool and BSMTP MAILER Interfaces

    SMTPPLUS is fully compatible with the documented VM SMTP spool and mailer interfaces.
  • Integration Points

    Spam and virus mitigation policies in SMTPPLUS are completely user-configurable, as are mapping of e-mail addresses to local VM users and the frequency with which the virus signature database is updated. All aspects of mail routing--not merely the recipient, but also inbound and outbound relaying decisions, host access decisions, and user authentication, can be set as site policy.
  • Easy Installation and Configuration Documentation

    The installation and configuration documentation for SMTPPLUS can viewed online here.


SMTPPLUS requires no software products beyond an IBM-supported version of VM/CMS, from z/VM 3.1 onward.


Delivery and Installation

SMTPPLUS is delivered in electronic form to Internet-connected sites. An easy-to-use installation program provides a simple installation process. SMTPPLUS is available for immediate shipment upon payment of the invoice.



SMTPPLUS is offered for a one-time fee plus maintanance. For complete information about charges, contact us.


Product Documentation


Where Can You Find Out More About SMTPPLUS?

A PDF version of the SMTPPLUS Installation and Configuration Guide is available here.