dovecot - Oct 2018 - Shared mailboxes - Can't open mailbox shared-boxes/user/name.lastname: Character not allowed in mailbox name: '.'

Hi,

I am trying to make shared folders work on my server (Ubuntu 18.04, 
Dovecot 1:2.2.33.2-1ubuntu4.1). Mails are on Maildir++ local filesystem 
with '.' as layout separator and ALL 100+ users logins fits a template 
name.lastname, with a dot in the middle.

I set up listescape but no luck. When I test with doveadm:

root at mail:/etc/dovecot/conf.d# doveadm acl debug -u 
marcio.merlone at a1.ind.br shared-boxes/user/name.lastname
doveadm(marcio.merlone at a1.ind.br): Error: Can't open mailbox 
shared-boxes/user/name.lastname: Character not allowed in mailbox name:
'.'
root at mail:/etc/dovecot/conf.d#

Is there something I can do besides changing layout separator?

Full dovecot -n output:

# 2.2.33.2 (d6601f4ec): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.4.21 (92477967)
# OS: Linux 4.15.0-36-generic x86_64 Ubuntu 18.04.1 LTS ext4
auth_gssapi_hostname = $ALL
auth_krb5_keytab = /etc/dovecot/dovecot.keytab
auth_master_user_separator = *
auth_mechanisms = plain ntlm login gssapi
auth_username_chars = 
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.@
auth_username_format = %Ln
dict {
 ? acl = mysql:/etc/dovecot/acl-dict-sql.conf
}
disable_plaintext_auth = no
dotlock_use_excl = no
first_valid_uid = 3000
hostname = smtp.a1.ind.br
imap_client_workarounds = tb-extra-mailbox-sep delay-newmail
last_valid_uid = 3000
lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes
lda_original_recipient_header = X-Original-To
mail_access_groups = vmail dovecot
mail_fsync = always
mail_gid = 3000
mail_location = 
maildir:/mnt/maildirs/%u/Maildir:INDEX=/mnt/maildirs/%u/index
mail_plugins = acl
mail_privileged_group = vmail
mail_server_admin = mailto:postmaster at a1.ind.br
mail_uid = 3000
mailbox_list_index = yes
mailbox_list_index_very_dirty_syncs = yes
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope 
encoded-character vacation subaddress comparator-i;ascii-numeric 
relational regex imap4flags copy include variables body enotify 
environment mailbox date index ihave duplicate mime foreverypart extracttext
mmap_disable = yes
namespace {
 ? list = yes
 ? location = 
maildir:%%h/Maildir:INDEX=~/Maildir/shared/%%u:INDEXPVT=~/Maildir/shared/%%u
 ? prefix = shared/%%u/
 ? separator = /
 ? subscriptions = no
 ? type = shared
}
namespace inbox {
 ? hidden = no
 ? inbox = yes
 ? list = yes
 ? location  ? 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  ? separator = /
 ? subscriptions = yes
 ? type = private
}
passdb {
 ? args = /etc/dovecot/master-users
 ? driver = passwd-file
 ? master = yes
 ? pass = yes
}
passdb {
 ? args = /etc/dovecot/dovecot-ldap.conf.ext
 ? driver = ldap
}
plugin {
 ? acl = vfile:/etc/dovecot/global-acls:cache_secs=300
 ? acl_shared_dict = proxy::acl
 ? listescape_char = \
 ? mail_log_events = delete undelete expunge copy mailbox_delete 
mailbox_rename
 ? mail_log_fields = uid box msgid size
 ? sieve = file:~/Maildir/sieve/;active=~/.dovecot.sieve
 ? sieve_before = /etc/dovecot/global.sieve
 ? sieve_max_actions = 32
 ? sieve_max_redirects = 4
}
postmaster_address = postmaster at a1.ind.br
protocols = " imap lmtp sieve sieve"
quota_full_tempfail = yes
service auth-worker {
 ? user = $default_internal_user
}
service auth {
 ? unix_listener /var/spool/postfix/private/auth {
 ??? group = postfix
 ??? mode = 0666
 ??? user = postfix
 ? }
 ? unix_listener auth-userdb {
 ??? mode = 0666
 ? }
}
service dict {
 ? unix_listener dict {
 ??? group = vmail
 ??? mode = 0660
 ??? user = vmail
 ? }
}
service imap-login {
 ? inet_listener imap {
 ??? port = 143
 ? }
 ? inet_listener imaps {
 ??? port = 993
 ??? ssl = yes
 ? }
 ? process_min_avail = 1
 ? service_count = 0
}
service imap {
 ? process_limit = 1024
}
service lmtp {
 ? unix_listener /var/spool/postfix/private/dovecot-lmtp {
 ??? group = postfix
 ??? mode = 0600
 ??? user = postfix
 ? }
 ? unix_listener lmtp {
 ??? mode = 0666
 ? }
}
service managesieve-login {
 ? inet_listener sieve {
 ??? port = 4190
 ? }
 ? process_min_avail = 1
 ? service_count = 0
}
service managesieve {
 ? process_limit = 1024
}
ssl_cert = </etc/letsencrypt/live/imap.a1.ind.br/fullchain.pem
ssl_cipher_list = 
ALL:!LOW:!SSLv2:!EXP:!aNULL:!RC4::!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS
ssl_client_ca_dir = /etc/ssl/certs
ssl_key =? # hidden, use -P to show it
submission_host = localhost
syslog_facility = local1
userdb {
 ? args = uid=3000 gid=3000 home=/mnt/maildirs/%Ln 
mail=maildir:/mnt/maildirs/%Ln/Maildir:INBOX=/mnt/maildirs/%Ln/Maildir 
allow_all_users=yes
 ? driver = static
}
protocol lmtp {
 ? info_log_path = /var/log/dovecot-lmtp.log
 ? mail_plugins = acl
}
protocol lda {
 ? mail_plugins = acl quota sieve acl listescape
}
protocol imap {
 ? mail_max_userip_connections = 300
 ? mail_plugins = acl quota imap_quota acl imap_acl listescape
}

Thanks, best regards.

-- 
*Marcio Merlone*