==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.3.2 OPENLDAP edition
- Deployed with the downloadable installer?
- Linux/BSD distribution name and version: Centos 8
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): LDAP
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? no
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I'm currently evaluating this product to migrate our existing mail server but I have issues with Active Directory integration using multiple domains.
It works fine with users that is the same with Windows AD default domain. However, if users is from other domain authentication failed.

I followed this guide but its only works for single domain integration:
https://docs.iredmail.org/active.direct … in-dovecot

Windows Active Directory Domain:

Default domain: corp.mydomain.com
user@mydomain.com

UPN suffixes:

mydomain1.com  - use@mydomain1.com
mydomain2.com  - user@mydomain2.com
mydomain3.com  - user@mydomain3.com

Configuration:

===========================================
/etc/postfix/ad_sender_login_maps.cf
===========================================

        server_host     = dc.corp.mydomain.com
    server_port     = 389
    version         = 3
    bind            = yes
    start_tls       = no
    bind_dn         = vmail
    bind_pw         = password_of_vmail
    search_base     = cn=users,dc=corp,dc=mydomain,dc=com
    scope           = sub
    query_filter    = (&(userPrincipalName=%s)(objectClass=person)(!(userAccountControl:1.2.840.113556.1.4.803:=2)))
    result_attribute= userPrincipalName
    debuglevel      = 0

===========================================
/etc/postfix/ad_virtual_mailbox_maps.cf
===========================================

        server_host     = dc.corp.mydomain.com
    server_port     = 389
    version         = 3
    bind            = yes
    start_tls       = no
    bind_dn         = vmail
    bind_pw         = passwd_of_vmail
    search_base     = cn=users,dc=corp,dc=mydomain,dc=com
    scope           = sub
    query_filter    = (&(objectclass=person)(userPrincipalName=%s))
    result_attribute= userPrincipalName
    result_format   = %d/%u/Maildir/
    debuglevel      = 0

=============================================
/etc/postfix/ad_virtual_group_maps.cf
=============================================

    server_host     = dc.corp.mydomain.com
    server_port     = 389
    version         = 3
    bind            = yes
    start_tls       = no
    bind_dn         = vmail
    bind_pw         = password_of_vmail
    search_base     = cn=users,dc=corp,dc=mydomain,dc=com
    scope           = sub
    #query_filter    = (&(objectClass=group)(mail=%s))
        query_filter = (&(objectClass=group)(sAMAccountName=%u))
    special_result_attribute = member
    #leaf_result_attribute = mail
    result_attribute= userPrincipalName
    debuglevel      = 0

=========================================
/etc/dovecot/dovecot-ldap.conf
=========================================

        hosts           = dc.corp.mydomain.com:389
    ldap_version    = 3
    auth_bind       = yes
    dn              = vmail
    dnpass          = passwd_of_vmail
    base            = cn=users,dc=corp,dc=mydomain,dc=com
    scope           = subtree
    deref           = never

    # Below two are required by command 'doveadm mailbox ...'
    iterate_attrs   = userPrincipalName=user
    iterate_filter  = (&(userPrincipalName=*)(objectClass=person)(!(userAccountControl:1.2.840.113556.1.4.803:=2)))

    user_filter     = (&(userPrincipalName=%u)(objectClass=person)(!(userAccountControl:1.2.840.113556.1.4.803:=2)))
    pass_filter     = (&(userPrincipalName=%u)(objectClass=person)(!(userAccountControl:1.2.840.113556.1.4.803:=2)))
    pass_attrs      = userPassword=password
    default_pass_scheme = CRYPT
    user_attrs      = =home=/var/vmail/vmail1/%Ld/%Ln/,=mail=maildir:~/Maildir/