set parameter per user

Hello,

My dovecot server (2.2.33.2) work with "lmtp_save_to_detail_mailbox = no" Now I would like to enable the feature for /some/ users.

Is that an option that could be set from an LDAP entry?

I tried the following:

modify my ldap schema to allow an optional attribute  

"lmtp-save-to-detail-mailbox"

in /etc/dovecot/ldap.conf
   user_attrs  = ...
                

=lmtp_save_to_detail_mailbox=%{ldap:lmtp-save-to-detail-mailbox:no}, =...

Now I set an ldapattribute "lmtp-save-to-detail-mailbox" with value
"yes" for some users.

Unfortunately messages to user+extension@domain are still delivered to INBOX/ while they should be delivered to INBOX/extension.

I also tried to make the attribute accessible vi pass_attr and
userdb_foo = ... because I use prefetch driver as userdb. I also disabled prefetching
at all but no luck :-/

any Ideas? Andreas