feat(postfix): implement virtual mailbox configuration for Dovecot LMTP

Updates the Postfix configuration to correctly handle virtual domains when Dovecot LMTP is enabled, moving away from local system delivery settings.

- Removes `postfix_mail_domain` from `postfix_mydestination` to prevent conflicts with virtual domain handling.
- Updates `main.cf` to set `virtual_transport`, `virtual_mailbox_domains`, and `virtual_mailbox_maps` instead of `mailbox_transport`.
- Adds a new template `virtual_mailbox_maps.j2` to authorize specific users defined in `dovecot_users`.
- Adds tasks to generate the virtual mailbox map file and run `postmap` upon changes.

tasks/main.yml

@@ -54,6 +54,29 @@
     - postfix_config
     - postfix_smarthost
 
+- name: "POSTFIX | Configure virtual mailbox maps"
+  when: dovecot_enabled | default(false) and dovecot_postfix_lmtp_enable | default(false)
+  ansible.builtin.template:
+    src: virtual_mailbox_maps.j2
+    dest: /etc/postfix/virtual_mailbox_maps
+    owner: root
+    group: root
+    mode: '0644'
+  notify: Restart Postfix
+  tags:
+    - postfix_config
+    - dovecot_config
+
+- name: "POSTFIX | Create hash map for virtual mailbox maps"
+  when: dovecot_enabled | default(false) and dovecot_postfix_lmtp_enable | default(false)
+  ansible.builtin.command:
+    cmd: postmap hash:/etc/postfix/virtual_mailbox_maps
+  changed_when: true
+  notify: Restart Postfix
+  tags:
+    - postfix_config
+    - dovecot_config
+
 - name: "DOVECOT | Install Dovecot packages"
   when: dovecot_enabled | default(false)
   ansible.builtin.apt: