passwd-file extra-fields: inbox=yes

[Michael Fox]

I'd like to implement the virtual plugin so that POP3 users can see emails
in their own inbox and a public namespace.  As I understand it, I need to
set "inbox=yes" separately, depending on which service the user is using.
With passwd-file flat files, this means:

userdb {
	args = ... /path/userdb.%s
}

userdb.imap:
	set the extra fields for each user =
userdb_namespace/inbox/inbox=yes

userdb.pop3:
	set the extra fields for each user =
userdb_namespace/virtual/inbox=yes

But without even getting to the virtual namespace part, I'm having
difficulty getting the extra fields setting to work for a regular IMAP user.


Specifically:
If I use the Dovecot default settings of namespace inbox, which includes
inbox=yes, and do NOT include the extra_fields value shown above, then IMAP
users can log in OK.

But if I comment out inbox=yes within namespace inbox, and then add the
extra fields to userdb.imap (as shown above), (and reload doveadm), then the
IMAP user is no longer able to login.  Thunderbird displays "Login to server
... failed." and I get the following in syslog (mail.err):

Aug  1 13:56:13 n6mef-gw dovecot: imap(mefimp at email.n6mef.org): Error: user
mefimp at email.n6mef.org: Initialization failed: namespace configuration
error: Duplicate namespace prefix: ""
Aug  1 13:56:13 n6mef-gw dovecot: imap(mefimp at email.n6mef.org): Error:
Invalid user settings. Refer to server log for more information.

I'm at a loss for what's wrong.  Can someone help?  
Userdb.imap test entry and doveconf -n below.

Thanks,
Michael



Userdb.imap:
mefimp::::Michael E Fox -
mefimp:::userdb_namespace=/namespace/inbox/inbox=yes


$ doveconf -n
# 2.2.9: /etc/dovecot/dovecot.conf
# OS: Linux 3.16.0-76-generic x86_64 Ubuntu 14.04.4 LTS
auth_mechanisms = cram-md5
auth_verbose = yes
mail_gid = vmail
mail_location = maildir:~/Maildir
mail_plugins = " quota"
mail_uid = vmail
namespace inbox {
  location =
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix =
}
passdb {
  args = /etc/dovecot/deny-users
  deny = yes
  driver = passwd-file
}
passdb {
  args = scheme=cram-md5 username_format=%n /etc/dovecot/auth.d/%d/passdb
  driver = passwd-file
}
plugin {
  quota = maildir:User quota
  quota_grace = 10%%
  quota_rule = *:storage=50MB
  quota_rule2 = Trash:storage=+10%%
  quota_status_nouser = DUNNO
  quota_status_overquota = 552 5.2.2 Mailbox is full
  quota_status_success = DUNNO
  quota_status_toolarge = 552 5.2.3 Message is too large
  quota_warning = storage=90%% quota-warning 90 %n %d
  quota_warning2 = storage=75%% quota-warning 75 %n %d
}
pop3_lock_session = yes
protocols = pop3 imap lmtp
service auth {
  unix_listener /var/spool/postfix/private/dovecot-auth {
    group = postfix
    mode = 0660
    user = postfix
  }
  unix_listener auth-userdb {
    group = vmail
    mode = 0600
    user = vmail
  }
}
service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0600
    user = postfix
  }
}
service pop3 {
  executable = pop3 postlogin
  process_limit = 25
}
service postlogin {
  executable = script-login /etc/dovecot/postlogin.sh
  group = vmail
  user = vmail
}
service quota-status {
  client_limit = 1
  executable = quota-status -p postfix
  inet_listener {
    port = 12340
  }
}
service quota-warning {
  executable = /etc/dovecot/quota-warning.sh
  user = vmail
}
ssl = required
ssl_cert = </opt/xsc/ssl/certs/n6mef-gw.crt
ssl_key = </opt/xsc/ssl/private/n6mef-gw.key
ssl_protocols = !SSLv2 !SSLv3
userdb {
  args = username_format=%n /etc/dovecot/auth.d/%d/userdb.%s
  default_fields = home=/var/vmail/%d/%n
  driver = passwd-file
}
verbose_ssl = yes
protocol lmtp {
  postmaster_address = xxxxxxxxxx
}
protocol imap {
  mail_max_userip_connections = 1
}
protocol pop3 {
  mail_max_userip_connections = 1
}
remote 192.168.7.0/24/24 {
  ssl = yes
}
remote 192.168.7.0/27/27 {
  ssl = no
}
$