[Dovecot] Migrating with dsync and INBOX.INBOX namespace issue

[Nikolai Schupbach]

I'm working on migrating IMAP users from Mirapoint Message Servers to Dovecot servers. The Mirapoint IMAP server uses INBOX as a namespace for private mailboxes. I created the same namespace in Dovecot, but when I migrate mailboxes dsync seems to ignore/miss the namespace on Mirapoint and I end up with all mailboxes under a INBOX.INBOX hierarchy.

Mirapoint Source Server
-----------------------
* OK server.name Mirapoint IMAP4 3.8.3-GA server ready
1 LOGIN test at test.com test
1 OK User logged in
2 NAMESPACE
* NAMESPACE (("INBOX." ".")) (("user." ".")) (("" "."))
2 OK Completed
3 LIST "" *
* LIST () "." "INBOX"
* LIST () "." "INBOX.Draft"
* LIST () "." "INBOX.Sent"
* LIST () "." "INBOX.Trash"
3 OK Completed

Running Dsync
-------------
# doveadm -v -o imapc_host=server.name imapc_user=test at test.com -o imapc_password=test backup -R -u test at test.com imapc:
dsync(test at test.com): Info: INBOX.INBOX.Sent: only in source (guid=7d3c7eaa71cdf47ee8a1192687cda8cd)
dsync(test at test.com): Info: INBOX.INBOX.Draft: only in source (guid=a6a03ff3d6ec9066b46013f4affb109a)
dsync(test at test.com): Info: INBOX.INBOX.Trash: only in source (guid=b36f688eae08506001091708006abe5a)
dsync(test at test.com): Info: INBOX: only in source (guid=c92f64f79f0d1ed01e6d5b314f04886c)

Dovecot Destination Server Post Dsync
-------------------------------------
* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE AUTH=PLAIN] Dovecot ready.
1 LOGIN test at test.com test
1 OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS MULTIAPPEND UNSELECT CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS SPECIAL-USE QUOTA ACL RIGHTS=texk] Logged in
2 NAMESPACE
* NAMESPACE (("INBOX." ".")) NIL NIL
2 OK Namespace completed.
3 LIST "" *
* LIST (\HasChildren) "." "INBOX"
* LIST (\HasNoChildren) "." "INBOX.INBOX.Sent"
* LIST (\HasNoChildren) "." "INBOX.INBOX.Trash"
* LIST (\HasNoChildren) "." "INBOX.INBOX.Draft"
3 OK List completed.

I noticed that Mirapoint IMAP also advertises a third empty namespace and I was wondering if this was causing it, but even if I explicitly set -n "INBOX." I still have the same issue.

Below is my doveconf -n output:

# 2.1.6: /usr/local/etc/dovecot/dovecot.conf
# OS: FreeBSD 9.0-RELEASE-p3 amd64  
auth_cache_negative_ttl = 0
auth_verbose = yes
default_vsz_limit = 512 M
deliver_log_format = subject=%s msgid=%m: %$
disable_plaintext_auth = no
imapc_features = rfc822.size
mail_gid = vmail
mail_home = /mailstore/domains/%d/%n
mail_location = mdbox:~/mdbox
mail_plugins = quota acl mail_log notify
mail_temp_dir = /var/tmp
mail_uid = vmail
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 ihave spamtest
namespace {
  inbox = yes
  location = 
  prefix = INBOX.
  separator = .
}
passdb {
  args = /usr/local/etc/dovecot/dovecot-ldap-passdb.conf
  driver = ldap
}
plugin {
  acl = vfile:/usr/local/etc/dovecot/global-acls
  mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename
  mail_log_fields = uid box msgid size
  quota = dict:User quota::file:%h/.dovecot-quota
  quota_warning = storage=95%% quota-warning 95 %u
  sieve = ~/.dovecot.sieve
  sieve_extensions = +spamtest
  sieve_max_redirects = 32
  sieve_spamtest_max_value = 10
  sieve_spamtest_status_header = X-Spam-Score
  sieve_spamtest_status_type = score
}
service auth-worker {
  user = $default_internal_user
}
service auth {
  client_limit = 5420
  unix_listener auth-userdb {
    group = vmail
    mode = 0600
    user = vmail
  }
  user = $default_internal_user
}
service imap-login {
  process_min_avail = 12
  service_count = 0
  vsz_limit = 512 M
}
service imap {
  process_limit = 4096
  vsz_limit = 512 M
}
service lmtp {
  process_min_avail = 12
  user = vmail
}
service pop3-login {
  process_min_avail = 12
  service_count = 0
  vsz_limit = 512 M
}
service pop3 {
  process_limit = 1024
  vsz_limit = 512 M
}
service quota-warning {
  executable = script /usr/local/bin/quota-warning
  unix_listener quota-warning {
    user = vmail
  }
  user = vmail
}
ssl = no
userdb {
  args = /usr/local/etc/dovecot/dovecot-ldap-userdb.conf
  driver = ldap
}
verbose_proctitle = yes
protocol imap {
  mail_max_userip_connections = 50
  mail_plugins = quota acl mail_log notify imap_quota imap_acl
}
protocol lmtp {
  mail_plugins = quota acl mail_log notify sieve
}

Any help would be much appreciated.

Regards, Nikolai.