[Mailman-Users] wrapper program

[camelia]

I installed mailman on our web server ( that is configured also like
mail server).
Everything looks OK.
When   i try to send a message to a mailinglist  I get:

list_name... aliased to :|export/mailman/mail/wrapper post name_lis"
"|/export/mailman/mail/wrapper post list_name"... Connecting to prog...
"|/export/mailman/mai/wrapper post list_name" ... Sent

but the message doesn't arrive to destination.
How works the wrapper  exactly ?
What can I do to check what happens ?