mm-handler-2.1.10 is based on the original mm-handler. See README.mm-handler for much important information that is not repeated here. This version was updated by David Champion to add the ability to select a subset of list addresses to accept and to add switches to not generate bounces for non-existent lists and unaccepted or invalid list addresses. It was further debugged and polished by Kenneth Porter . Kenneth added syslog logging using the perl Unix::Syslog module (available from CPAN and other repositories). If you don't have that module, you must either install it or remove the module references and syslog references from mm-handler-2.1.10. This is a work in progress. The major thing left to do is to arrange for it to exit with an appropriate exit code (e.g. EX_NOUSER or EX_UNAVAILABLE) when the message is undeliverable. This in turn requires that mm-handler be invoked separately for each message recipient address. The sample mailman.mc file is set up this way and mentions that the 'm' and 'n' flags should not be used, but mm-handler contains an address processing loop in case the 'm' flag is included in it's invocation. This should be changed to log an appropriate error if mm-handler is invoked with multiple recipient addresses. See the threads "before next release: disable backscatter in default installation", "anti-backscatter mm-handler ..." and "mm-handler 2.1.10 ..." at for background and further information. Note - 2011-01-04: mm-handler-2.1.10 has been patched with the patch in the bug report at which see.