Hi Folks !

I finaly resolve my problem ! 😊

First of all I had to modify namespaces :

#######################################################

namespace inbox {

  inbox = yes

  location =

  mailbox Archive {

    auto = subscribe

    special_use = \Archive

  }

  mailbox Drafts {

    auto = subscribe

    special_use = \Drafts

  }

  mailbox Junk {

    auto = subscribe

    special_use = \Junk

  }

  mailbox Sent {

    auto = subscribe

    special_use = \Sent

  }

  mailbox Trash {

    auto = subscribe

    special_use = \Trash

  }

  prefix = INBOX/

  separator = /

  subscriptions = yes

  type = private

}

namespace partage {

  list = children

  location = maildir:/mnt/mail/vmail/%%d/%%n:INDEXPVT=/mnt/mail/vmail/%d/%n/shared/%%u

  prefix = shared/%%u/

  separator = /

  subscriptions = yes

  type = shared

}

#######################################################

Also change the « replication_dsync_parameters » in aim to syncronize only the Private namespace :

==> replication_dsync_parameters = -d -n inbox -l 30 -U

I change the sharing command from « acl set » to « acl add »

AND THE MOST IMPORTANT ==> RUN THE COMMAND ON THE 2 SERVER because of active/active réplication…

==> doveadm acl add -u user2@exemple.fr INBOX user=user1@exemple.fr admin create delete expunge insert lookup post read write write-deleted write-seen

Hope this may help if someone is faced to the same problem

Best regards

Laurent