Response is a set of tools to handle automatic email responses, also called "Out of Office", "Vacation", or "Autoreply" messages. Response tries hard to do that the correct way, i.e. not responding to messages that should not be responded to. All of the validation code can be easily modified to suite your needs, but the project tries hard to ship sane defaults. It is designed for many virtual users and multiple mail servers, but works just fine for small deployments. Configuration and response state is stored in an RDBMS.
spmfilter is a mail filtering framework. It attempts to be a general filtering framework for any purpose. The API enables spmfilter plugins to access messages as they are being processed by the MTA. This allows them to examine and modify message content and meta-information during the SMTP transaction. Plugins are loaded at runtime and can be processed in any sequence. The processing chain can also be altered by a single plugin, for example if the plugin has to stop further processing.
Z1 CertServer (formerly Z1 Backbone Of Trust CertServer) is a server-based software solution for the storage and administration of X.509 certificates and OpenPGP keys. It targets customers who use a public key infrastructure (based on X.509 or OpenPGP) and who want to take advantage of the central access to certificates. It also automatically validates certificates by querying certificate revocation lists (CRLs) from the issuing trust centers, or by using OCSP (Online Certificate Status Protocol). Java and C/C++ SDKs are provided. It is available as pre-installed hardware or a virtual appliance, with evaluation packages for Debian and Solaris.
lib_MTA is a BASH function library for dealing with email. It provides support for unencrypted and TLS-encrypted relaying of email with attachments, special mailing list filtering, and From address spoofing. The installation automatically sets up a mailing list filtering infrastructure that can be enabled with a few simple steps. Example scripts for relaying email and filtering mailing lists are included in the package with the library. Desktop users can employee a simple script to send email to remote addresses without the need for a local MTA, provided they have relay access via Gmail or their ISP.
OpenFWTK is an application proxy toolkit which inherits the ideology of TIS fwtk and maintains API backwards compatibility. The design goal is to make it simple yet powerful; no performance hacks are allowed in the code and library dependencies are reduced to a minimum. It is a true application layer filter. It features unified pluggable content inspection for the most frequently used protocols, NAC (Network Admission Control), and the ability to define fine-grained Internet access policy based on browser identification.