I need help. I’m trying to reproduce an issue, but I keep hitting so many errors that I’m completely stuck. I'm reproducing this on a single machine.

1. Setting up the environment:

groupadd -g 500 vmail && useradd -M -u 500 -g vmail -s /bin/false vmail && mkdir -p /tmp/mail && chown vmail:vmail /tmp/mail

2. Starting up Dovecot.
3. User mailboxes don’t exist yet.
4. Saving an email via CLI:

doveadm save -u user1 -m INBOX /tmp/1.eml

5. Checking the email UID, but it’s missing:

curl -u "user1:hello" -k imap://localhost:143/INBOX -X "UID SEARCH ALL"

• SEARCH

6. Saving the exact same email via APPEND:

curl -u "user1:hello" -k imap://localhost:143/INBOX --upload-file /tmp/1.eml

7. Now the UID shows up. But which one? What’s the difference here?

curl -u "user1:hello" -k imap://localhost:143/INBOX -X "UID SEARCH ALL"

• SEARCH 1

8. Restarting Dovecot.
9. Checking the UID again. And it's gone! Where did it go? It's right there in the indexes.

curl -u "user1:hello" -k imap://localhost:143/INBOX -X "UID SEARCH ALL"

• SEARCH

10. The email files are right there in new/. The entries are in dovecot-uidlist. They're also in dovecot.index.cache.
11. I share rights with user2.

doveadm acl add -u user1 INBOX user=user2 lookup read write write-seen write-deleted insert post expunge create delete admin

12. The entry in /tmp/mail/shared.db showed up. However, user2 still can't see that user1's INBOX has been shared with them. No shared namespace.

curl -u "user2:hello" -k imap://localhost:143/

• LIST (\HasNoChildren) "/" INBOX

13. When I try to connect the same way imapc does, I get an error saying the mailbox doesn't exist.

curl -u "user1*user2:hello" -k imap://localhost:143/INBOX -X "UID SEARCH ALL" A003 NO [NONEXISTENT] Mailbox doesn't exist: INBOX (0.002 + 0.000 + 0.001 secs)

14. But this is not true.

$ tree -a /tmp/mail/ /tmp/mail/ ├── shared.db └── user1 ├── dovecot-acl-list ├── dovecot.list.index.log ├── dovecot-uidvalidity ├── dovecot-uidvalidity.6a4029ad └── .INBOX ├── cur ├── dovecot-acl ├── dovecot.index.cache ├── dovecot.index.log ├── dovecot-uidlist ├── maildirfolder ├── new │   └── 1782589869.M440304P1305393.mail.test.server,S=3517,W=3584 └── tmp

15. From debug log. I did not set this options. Like it is something inside logic.

Debug: Ignored unknown userdb field: master_user=user2

16. Here’s what my config looks like.

dovecot_config_version = 2.4.4 dovecot_storage_version = 2.4.4

mail_debug = yes

acl_driver = vfile auth_master_user_separator = * auth_allow_cleartext = yes mail_driver = maildir mail_home = /tmp/mail/%{user} mail_path = ~ mail_inbox_path = ~/.INBOX mail_index_path = ~ mail_control_path = ~ mail_uid = vmail mail_gid = vmail first_valid_uid = 500 mail_shared_explicit_inbox = yes

imapc_host = 127.0.0.1 imapc_master_user = %{user} imapc_password = any imapc_port = 143

service auth { unix_listener auth-userdb { mode = 0660 user = vmail group = vmail } unix_listener auth-master { mode = 0660 group = vmail } }

acl_sharing_map { dict file { path = /tmp/mail/shared.db } }

protocols { imap = yes }

mail_plugins { acl = yes }

protocol imap { mail_plugins { imap_acl = yes } }

service imap-login { inet_listener imaps { port = 0 } }

passdb anypass-imapc { master = yes driver = static fields { nopassword = yes userdb_acl_user = %{auth_user} } }

passdb anypass-users { driver = static fields { nopassword = yes } }

namespace inbox { inbox = yes separator = / }

namespace shared { type = shared separator = / prefix = shared/$user/ acl_ignore = yes list = children subscriptions = no mail_driver = imapc mail_path = ~/shared/%{owner_user} mail_index_path = ~/shared/%{owner_user} mail_control_path = ~/shared/%{owner_user} }

Thanks to Timo's advise (much appreciated!), I shifted the mail root to /mail dir. Now I have a simplest config where the bug triggers flawlessly. Feel free to test on a clean Debian machine; it’s a 100% reproducible.

1. Setting up the environment:

groupadd -g 500 vmail && useradd -M -u 500 -g vmail -s /bin/false vmail && mkdir -p /mail && chown vmail:vmail /mail

2. Copy-paste dovecot.conf from the bottom of this mail & start dovecot.
3. Save eml to INBOX of user1 with CLI.

doveadm save -u user1 -m INBOX /tmp/1.eml

4. Both works: saving with APPEND too.

curl -u "user1:hello" -k imap://localhost:143/INBOX --upload-file /tmp/1.eml

5. Share rights with user2.

doveadm acl add -u user1 INBOX user=user2 lookup read write write-seen write-deleted insert post expunge create delete admin

6. Try SEARCH ALL & SORT from owner. It works pretty well.

curl -u "user1:hello" -k imap://localhost:143/INBOX -X "UID SEARCH ALL" SEARCH 1 2 curl -u "user1:hello" -k imap://localhost:143/INBOX -X "UID SORT (REVERSE ARRIVAL) US-ASCII NOT DELETED" SORT 2 1

7. Try same thing over imapc from user2 (over shared namespace).

curl -u "user2:hello" -k imap://localhost:143/shared/user1/INBOX -X "UID SEARCH ALL" SEARCH 1 2 curl -u "user2:hello" -k imap://localhost:143/shared/user1/INBOX -X "UID SORT (REVERSE ARRIVAL) US-ASCII NOT DELETED" SORT

SORT does not return any UIDs, but SEARCH does. Do you see that? Can You help with this, please?

dovecot_config_version = 2.4.4
dovecot_storage_version = 2.4.4

mail_debug = yes

acl_driver = vfile
auth_master_user_separator = *
auth_allow_cleartext = yes
mail_driver = maildir
mail_home = /mail/%{user}
mail_path = ~
mail_inbox_path = ~/.INBOX
mail_index_path = ~
mail_control_path = ~
mail_uid = vmail
mail_gid = vmail
first_valid_uid = 500
mail_shared_explicit_inbox = yes

imapc_host = 127.0.0.1
imapc_master_user = %{user}
imapc_password = any
imapc_port = 143

service auth {
  unix_listener auth-userdb {
    mode = 0660
    user = vmail
    group = vmail
  }
  unix_listener auth-master {
    mode = 0660
    group = vmail
  }
}

acl_sharing_map {
  dict file {
    path = /mail/shared.db
  }
}

protocols {
  imap = yes
}

mail_plugins {
  acl = yes
}

protocol imap {
  mail_plugins {
    imap_acl = yes
  }
}

service imap-login {
  inet_listener imaps {
    port = 0
  }
}

passdb anypass-imapc {
  master = yes
  driver = static
  fields {
    nopassword = yes
    userdb_acl_user = %{auth_user}
  }
}

passdb anypass-users {
  driver = static
  fields {
    nopassword = yes
  }
}

namespace inbox {
  inbox = yes
  separator = /
}

namespace shared {
  type = shared
  separator = /
  prefix = shared/$user/
  acl_ignore = yes
  list = children
  subscriptions = no
  mail_driver = imapc
  mail_path = ~/shared/%{owner_user}
  mail_index_path = ~/shared/%{owner_user}
  mail_control_path = ~/shared/%{owner_user}
}

Thank you very much!