Re: How can I use /etc/passwd auth for linux users and a passwd-file for virtual mailbox users?

3 Jan 2026

      Yes I had thought of that idea too ... but I have a preference for creating
the home then adding in a link to the required location.
It creates the opportunity for creating an 'actual' home in the future if
required.
Le ven. 2 janv. 2026 à 22:12, Chris Twinn <chris@twinn.co.uk> a écrit :
...
Would that not be akin to a nologin shell?
Set the user home to /var/postfix/virtual/example.net/usename on creation.
useradd -d  /var/postfix/virtual/example.net/username -s /sbin/nologin
username
Personally I prefer /home/example.net/username but.
Bypassing creating a link from /home/username to the /var....
User can then be verfied by the system for mails but can't actually access
the system. Dovecot/postfix reads the home dir and delivers mail where
required.
Again I'm sure there are
other more experienced admins.....
On 2 January 2026 19:35:39 GMT, David Myers via dovecot <
dovecot@dovecot.org> wrote:
...
I was wondering if this was a good use case for the creation of a user
without a dedicated home directory.
The user will not be able to 'log in' in the traditional way, but they
would have an entry in /etc/passwd. Then you would only need to create a
link from /home/user into your selected location (in your instance
/var/postfix/virtual/example.net/[user <http://example.net/%5Buser> <http://example.net/user>Name] ).
please note : this isn't something that I have done, but I'm sure there are
other more experienced admins on this list that will pipe up if this is not
a good solution, and explain why its not, and propose alternatives.
Le mer. 31 déc. 2025 à 09:55, animerrill--- via dovecot <dovecot@dovecot.org>
a écrit :
I simply define my virtual domains in Postfix:
...
...

VIRTUAL DOMAINS
virtual_alias_domains = new.domain
virtual_alias_maps = hash:/etc/postfix/virtual
Then, in /etc/postfix/virtual, I add the alias:
newuser@new.domain   newuser
And that’s it.
Could you share your doveconf -n?
That set up is different than what I am trying to achieve. You have a
virtual alias set up, which redirects mail from an email address to an
arbitrary linux user. I am trying to avoid creating linux users for every
email account, which is why I need to be able to use dovecot's multiple
authentication database feature to facilitate virtual mailboxes. Here is
that section from my /etc/postfix/main.cf:
virtual_mailbox_domains = example.net
virtual_uid_maps = static:1001
virtual_gid_maps = static:1001
virtual_mailbox_base = /var/postfix/virtual
virtual_mailbox_maps = hash:/etc/postfix/virtual/recipients
virtual_alias_maps = hash:/etc/postfix/virtual/aliases
virtual_alias_domains = hash:/etc/postfix/virtual/domains

Then the mailbox is defined in /etc/postfix/virtual/recipients:
user@example.net    example.net/user

Which means that rather than being set up as a linux user with a /home
directory, user@example.net should have a virtual mailbox in
/var/postfix/virtual/example.net/user. This actually works as far as
postfix is concerned, and as the root user I can peek in that folder to see
a message sent to it from my personal email account. Then here is doveconf  -n:
# 2.4.1-4 (7d8c0e5759): /etc/dovecot/dovecot.conf
# Pigeonhole version 2.4.1-4 (0a86619f)
# OS: Linux 6.12.57+deb13-amd64 x86_64 Debian 13.2
# Hostname: example.com
dovecot_config_version = 2.4.1
auth_mechanisms = plain login
auth_username_format = %{user}
dovecot_storage_version = 2.4.1
mail_driver = sdbox
mail_inbox_path = ~/Mail/Inbox
mail_path = ~/Mail
protocols = imap
ssl = required
ssl_server {
  cert_file = /etc/letsencrypt/live/mail.example.com/fullchain.pem
  dh_file = /usr/share/dovecot/dh.pem
  key_file = /etc/letsencrypt/live/mail.example.com/privkey.pem
  prefer_ciphers = server
}
userdb passwd-file {
  passwd_file_path = /etc/dovecot/passwd/%{user | domain}
}
userdb passwd {
}
passdb passwd-file {
  passwd_file_path = /etc/dovecot/passwd/%{user | domain}
}
passdb pam {
}
namespace inbox {
  inbox = yes
  mailbox Drafts {
    auto = subscribe
    special_use = "\\Drafts"
  }
  mailbox Junk {
    auto = subscribe
    autoexpunge = 30d
    special_use = "\\Junk"
  }
  mailbox Sent {
    auto = subscribe
    special_use = "\\Sent"
  }
  mailbox Trash {
    special_use = "\\Trash"
  }
  mailbox Archive {
    special_use = "\\Archive"
  }
}
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
}
protocol lda {
  mail_plugins = sieve
}
protocol lmtp {
  mail_plugins = sieve
}
protocol pop3 {
  pop3_no_flag_updates = yes
  pop3_uidl_format = UID%{uid}-%{uidvalidity}
}
sieve_script default {
}

Basically the problem is that this virtual mailbox user has a mailbox that
receives mail, but the user cannot log onto their account with an email
client. My guess is that I either have misconfigured the userdb and/or
passdb entries in the dovecot.conf file, or the passwd-file at
/etc/dovecot/passwd/example.net I created is not formatted correctly,
because the ultimate problem is that the system cannot authenticate the
user when they attempt to connect via imap/smtp. From all of the
documentation and help threads referenced in my first message, I cannot
tell what I've done wrong and I'm at a total loss.
Thanks for the prompt reply. This is my first time using one of these mail
lists, so I did not see you responded right away.
dovecot mailing list -- dovecot@dovecot.org
To unsubscribe send an email to dovecot-leave@dovecot.org
Yes I had thought of that idea too ... but I have a preference for
creating the home then adding in a link to the required location.
It creates the opportunity for creating an 'actual' home in the future if
required.
Le ven. 2 janv. 2026 `a 22:12, Chris Twinn <[1]chris@twinn.co.uk> a
ecrit :
 Would that not be akin to a nologin shell?

 Set the user home to /var/postfix/virtual/[2]example.net/usename on
 creation.

 useradd -d  /var/postfix/virtual/[3]example.net/username -s
 /sbin/nologin username

 Personally I prefer /home/[4]example.net/username but.

 Bypassing creating a link from /home/username to the /var....

 User can then be verfied by the system for mails but can't actually
 access the system. Dovecot/postfix reads the home dir and delivers mail
 where required.

 Again I'm sure there are
 other more experienced admins.....

 On 2 January 2026 19:35:39 GMT, David Myers via dovecot
 &lt;[5]dovecot@dovecot.org> wrote:
I was wondering if this was a good use case for the creation of a user
without a dedicated home directory.
The user will not be able to 'log in' in the traditional way, but they
would have an entry in /etc/passwd. Then you would only need to create a
link from /home/user into your selected location (in your instance
/var/postfix/virtual/[6]example.net/[user <[7]http://example.net/user>Name] ).
please note : this isn't something that I have done, but I'm sure there are
other more experienced admins on this list that will pipe up if this is not
a good solution, and explain why its not, and propose alternatives.
Le mer. 31 dec. 2025 `a 09:55, animerrill--- via dovecot <[8]dovecot@dovecot.org>
a ecrit :
I simply define my virtual domains in Postfix:

VIRTUAL DOMAINS

virtual_alias_domains = new.domain
virtual_alias_maps = hash:/etc/postfix/virtual
Then, in /etc/postfix/virtual, I add the alias:
newuser@new.domain   newuser
And that's it.
Could you share your doveconf -n?
That set up is different than what I am trying to achieve. You have a
virtual alias set up, which redirects mail from an email address to an
arbitrary linux user. I am trying to avoid creating linux users for every
email account, which is why I need to be able to use dovecot's multiple
authentication database feature to facilitate virtual mailboxes. Here is
that section from my /etc/postfix/[9]main.cf:
virtual_mailbox_domains = [10]example.net
virtual_uid_maps = static:1001
virtual_gid_maps = static:1001
virtual_mailbox_base = /var/postfix/virtual
virtual_mailbox_maps = hash:/etc/postfix/virtual/recipients
virtual_alias_maps = hash:/etc/postfix/virtual/aliases
virtual_alias_domains = hash:/etc/postfix/virtual/domains

Then the mailbox is defined in /etc/postfix/virtual/recipients:
[11]user@example.net    [12]example.net/user

Which means that rather than being set up as a linux user with a /home
directory, [13]user@example.net should have a virtual mailbox in
/var/postfix/virtual/[14]example.net/user. This actually works as far as
postfix is concerned, and as the root user I can peek in that folder to see
a message sent to it from my personal email account. Then here is doveconf   -n:
# 2.4.1-4 (7d8c0e5759): /etc/dovecot/dovecot.conf
# Pigeonhole version 2.4.1-4 (0a86619f)
# OS: Linux 6.12.57+deb13-amd64 x86_64 Debian 13.2
# Hostname: [15]example.com
dovecot_config_version = 2.4.1
auth_mechanisms = plain login
auth_username_format = %{user}
dovecot_storage_version = 2.4.1
mail_driver = sdbox
mail_inbox_path = ~/Mail/Inbox
mail_path = ~/Mail
protocols = imap
ssl = required
ssl_server {
  cert_file = /etc/letsencrypt/live/[16]mail.example.com/fullchain.pem
  dh_file = /usr/share/dovecot/dh.pem
  key_file = /etc/letsencrypt/live/[17]mail.example.com/privkey.pem
  prefer_ciphers = server
}
userdb passwd-file {
  passwd_file_path = /etc/dovecot/passwd/%{user | domain}
}
userdb passwd {
}
passdb passwd-file {
  passwd_file_path = /etc/dovecot/passwd/%{user | domain}
}
passdb pam {
}
namespace inbox {
  inbox = yes
  mailbox Drafts {
    auto = subscribe
    special_use = "\\Drafts"
  }
  mailbox Junk {
    auto = subscribe
    autoexpunge = 30d
    special_use = "\\Junk"
  }
  mailbox Sent {
    auto = subscribe
    special_use = "\\Sent"
  }
  mailbox Trash {
    special_use = "\\Trash"
  }
  mailbox Archive {
    special_use = "\\Archive"
  }
}
service auth {
  unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
  }
}
protocol lda {
  mail_plugins = sieve
}
protocol lmtp {
  mail_plugins = sieve
}
protocol pop3 {
  pop3_no_flag_updates = yes
  pop3_uidl_format = UID%{uid}-%{uidvalidity}
}
sieve_script default {
}

Basically the problem is that this virtual mailbox user has a mailbox that
receives mail, but the user cannot log onto their account with an email
client. My guess is that I either have misconfigured the userdb and/or
passdb entries in the dovecot.conf file, or the passwd-file at
/etc/dovecot/passwd/[18]example.net I created is not formatted correctly,
because the ultimate problem is that the system cannot authenticate the
user when they attempt to connect via imap/smtp. From all of the
documentation and help threads referenced in my first message, I cannot
tell what I've done wrong and I'm at a total loss.
Thanks for the prompt reply. This is my first time using one of these mail
lists, so I did not see you responded right away.

dovecot mailing list -- [19]dovecot@dovecot.org
To unsubscribe send an email to [20]dovecot-leave@dovecot.org
References
Visible links

mailto:chris@twinn.co.uk
http://example.net/usename
http://example.net/username
http://example.net/username
mailto:dovecot@dovecot.org
http://example.net/%5Buser
http://example.net/user
mailto:dovecot@dovecot.org
http://main.cf/
http://example.net/
mailto:user@example.net
http://example.net/user
mailto:user@example.net
http://example.net/user
http://example.com/
http://mail.example.com/fullchain.pem
http://mail.example.com/privkey.pem
http://example.net/
mailto:dovecot@dovecot.org
mailto:dovecot-leave@dovecot.org

Re: How can I use /etc/passwd auth for linux users and a passwd-file for virtual mailbox users?

David Myers

VIRTUAL DOMAINS

Thanks for the prompt reply. This is my first time using one of these mail lists, so I did not see you responded right away.