Hello!

I'm using 2 namespaces, "inbox" for INBOX and it's subfolders and "special" containing folders like Sent, Junk or Drafts.  Though both use mdbox I decided to represent those namespaces in different locations "mdbox:~/mail" and "mdbox:~/mail_special_folders". The main reason to use 2 namespaces was to keep special_use folders out of INBOX by using the prefix attribute -- it's rather cosmetic. 

├── INBOX
│   ├── SubFolder1
│   ├── SubFolder2
│   └── SubFolder3
├── Sent
├── Trash
├── Drafts
├── Junk
├── Templates
├── This is Ham
└── Report Spam

Now I want to export the emails of some former users to common known maildir or mbox format to be able to hand them over on CD. The problem is that a conversion with doveadm backup fails. I guess this is due to namespace special which is configured with a manual location attribute instead of utilising mail_location. But even telling doveadm to backup only one namespace leads to the identical error (extract of debug message at bottom). 

As this is a RHEL7 server, the dovecot version is an old 2.2.10 and I don't expect software debugging -- I just ask if I did some misconfiguration or a failure in the command.
I already thought of merging the locations of both namespaces. Yet, I'm not sure how to achieve this. 

From /etc/dovecot/conf.d/10-mail.conf

mail_location = mdbox:~/mail

namespace inbox {
  type = private
  hidden = no
  ignore_on_failure = no
  inbox = yes
  list = yes
  location =
  prefix = INBOX/
  separator = /
  subscriptions = yes
}

namespace special {
  type = private
  hidden = no
  ignore_on_failure = no
  inbox = no
  list = yes
  location = mdbox:~/mail_special_folders
  prefix = 
  separator = /
  subscriptions = yes
}


HOME is set by LDAP
user_attrs = =home=/srv/mail/%Ld/%Ln,=uid=20000,=gid=20000,imapQuota=quota_rule=*:storage=%$G


Identical debug messages of following commands:

# dsync -Dv backup -u bob@cs.sbg.ac.at maildir:/home/Mailexport/bob
or
# doveadm -Dv backup -u bob@cs.sbg.ac.at maildir:/home/Mailexport/bob
or
# doveadm -Dv  backup -u bob@cs.sbg.ac.at -n inbox maildir:/home/Mailexport/bob
or 
# doveadm -Dv  backup -u bob@cs.sbg.ac.at -n special maildir:/home/Mailexport/bob

...
doveadm(bob@cs.sbg.ac.at): Debug: Namespace inbox: type=private, prefix=INBOX/, sep=/, inbox=yes, hidden=no, list=yes, subscriptions=yes location=mdbox:~/mail
doveadm(bob@cs.sbg.ac.at): Debug: fs: root=/srv/mail/cs.sbg.ac.at/bob/mail, index=, indexpvt=, control=, inbox=, alt=
doveadm(bob@cs.sbg.ac.at): Debug: Namespace special: type=private, prefix=, sep=/, inbox=no, hidden=no, list=yes, subscriptions=yes location=mdbox:~/mail_special_folders
doveadm(bob@cs.sbg.ac.at): Debug: fs: root=/srv/mail/cs.sbg.ac.at/bob/mail_special_folders, index=, indexpvt=, control=, inbox=, alt=
doveadm(bob@cs.sbg.ac.at): Debug: Namespace INBOX/: Using permissions from /srv/mail/cs.sbg.ac.at/bob/mail: mode=0774 gid=default
dsync(bob@cs.sbg.ac.at): Debug: Effective uid=20000, gid=20000, home=/srv/mail/cs.sbg.ac.at/bob
dsync(bob@cs.sbg.ac.at): Debug: Quota root: name=User quota backend=dict args=:file:/srv/mail/cs.sbg.ac.at/bob/dovecot-quota
...
dsync(bob@cs.sbg.ac.at): Debug: Namespace inbox: type=private, prefix=INBOX/, sep=/, inbox=yes, hidden=no, list=yes, subscriptions=yes location=maildir:/home/Mailexport/bob
dsync(bob@cs.sbg.ac.at): Debug: maildir++: root=/home/Mailexport/bob, index=, indexpvt=, control=, inbox=/home/Mailexport/bob, alt=
dsync(bob@cs.sbg.ac.at): Debug: Namespace special: type=private, prefix=, sep=/, inbox=no, hidden=no, list=yes, subscriptions=yes location=mdbox:~/mail_special_folders
dsync(bob@cs.sbg.ac.at): Debug: fs: root=/srv/mail/cs.sbg.ac.at/bob/mail_special_folders, index=, indexpvt=, control=, inbox=, alt=
dsync(bob@cs.sbg.ac.at): Error: Both source and destination mail_location points to same directory: /srv/mail/cs.sbg.ac.at/bob/mail_special_folders/mailboxes

Many thanks for any hint
Martin