[Mailman-Developers] probleme install

[Smati Beghoura]

Hello,
I'm French. The following text was translated with Google Translate.
Allow me to contact you because I have a problem in the configuration
mailman / postfix.
I have a new server. Config: I am under release3 CentOS 6.4 + webmin. I
asked a technician to deal with the migration of my sites from the old
server to it, but unfortunately, even if the sites work now, he somewhat
"broken" the distrib. So that I had no mailman. So I decided to remove and
reinstall mailman. Mailman now works with a list (mailman default) +
newsletter. Postfix on, if I send myself an email through Outlook
postmaster at hellovoyance.com reserved area on postfix) I get well email.
However, if I send an email to the list (newsletter at hellovoyance.com)
Outlook me a mail with return "user unknown". The detail of this is as
follows:

Reporting-MTA: dns; ns2275743.ovh.net

 

X-Postfix-Queue-ID: 5521962ED9

X-Postfix-Sender: rfc822; postmaster at hellovoyance.com

Arrival-Date: Fri, 29 Nov 2013 11:58:54 +0100 (CET)

Final-Recipient: rfc822; newsletter at hellovoyance.com

Original-Recipient: rfc822;newsletter at hellovoyance.com

Action: failed

Status: 5.1.1

Diagnostic-Code: x-unix; user unknow

 

I would like your opinion, because I admit that I am lost. I am novice but
trying to do it myself with the means that are given to me.
Thanking you in advance for your reply 

Regards 

SmatiBeghoura
PS: if I must re-install, how to remove mailman properly and with precise
installation documentation with my current setup?
PPS: for information, there is also a database whose name is "mail". On this
basis, there is the following tables:

"admin", "alias", "alias_domain", "config", "domain, "domain_admins",
"fetchmail", "log", "mailbox", "mailing", "quota", "quota2", "vacation" "
vacation_notification"