Hi,
N.B. Sorry if it's a duplicate post. I didn't receive the message I sent to the list. Probably because it was done before I change from digest to single.
Any way. I really need your help.
Back to the message :
Installed mailman 2.1.13, via macports, on snow leopard ( 10.6.7) with success. Same results following the procedure Larry Stone described on http://www.mail-archive.com/mailman-users@python.org/msg56923.html
Everything is working fine except for the integration with communigate. Error message from communigate : failed on 'mailman post testlist@domain.com'. Error Code=external processing failed
( pathname of the wrapper : /opt/local/libexec/mailman/mail )
The answer from the communicate discussion list is :
" Make sure that your program reads everything from the standard input up to EOF, exits with zero status code and does not output to the STDERR stream."
Extract from the communicate documentation : "The message text (including the message headers and the message body) is passed to the external application as its standard input. 
Note: the application must read the entire stdin data stream, otherwise message processing fails. When the external application completes, the PIPE module reads and discards the application standard output. Make sure that your application does not write anything to its standard output, so it is not blocked when the communication channel (pipe) buffer between the application and the Server is full."
Thanks in advance for any help and hints to use mailman with communigate.
P.S. Same results with mailman 2.1.14