feat: add support for Dovecot IMAP/POP3 configuration

Introduces functionality to install and configure Dovecot alongside Postfix to provide IMAP/POP3 services.

Changes include:
- Added tasks to install Dovecot packages (core, imapd, pop3d, lmtpd).
- Added templates for main configuration and conf.d files (auth, master, ssl, mail).
- Defined default variables for protocols, SSL settings, and Maildir location.
- Enabled Postfix SASL and LMTP integration options.
- Added a handler to restart the Dovecot service.
- Updated README.md with the new configuration variables and usage instructions.

templates/10-auth.conf.j2

@@ -0,0 +1,7 @@
+# Dovecot authentication configuration
+# Ansible managed: {{ ansible_managed }}
+
+disable_plaintext_auth = {{ 'yes' if dovecot_ssl == 'required' else 'no' }}
+auth_mechanisms = {{ dovecot_auth_mechanisms }}
+
+!include auth-system.conf.ext

templates/10-mail.conf.j2

@@ -0,0 +1,7 @@
+# Dovecot mail location configuration
+# Ansible managed: {{ ansible_managed }}
+
+mail_location = {{ dovecot_mail_location }}
+namespace inbox {
+  inbox = yes
+}

templates/10-master.conf.j2

@@ -0,0 +1,51 @@
+# Dovecot master configuration
+# Ansible managed: {{ ansible_managed }}
+
+service imap-login {
+  inet_listener imap {
+    port = 143
+  }
+  inet_listener imaps {
+    port = 993
+    ssl = yes
+  }
+}
+
+service pop3-login {
+  inet_listener pop3 {
+    port = 110
+  }
+  inet_listener pop3s {
+    port = 995
+    ssl = yes
+  }
+}
+
+service lmtp {
+  unix_listener /var/spool/postfix/private/dovecot-lmtp {
+    mode = 0600
+    user = postfix
+    group = postfix
+  }
+}
+
+service auth {
+  unix_listener /var/spool/postfix/private/auth {
+    mode = 0660
+    user = postfix
+    group = postfix
+  }
+
+  unix_listener auth-userdb {
+    mode = 0600
+    user = vmail
+  }
+}
+
+service auth-worker {
+}
+
+service dict {
+  unix_listener dict {
+  }
+}

templates/10-ssl.conf.j2

@@ -0,0 +1,6 @@
+# Dovecot SSL configuration
+# Ansible managed: {{ ansible_managed }}
+
+ssl = {{ dovecot_ssl }}
+ssl_cert = {{ dovecot_ssl_cert }}
+ssl_key = {{ dovecot_ssl_key }}

templates/dovecot.conf.j2

@@ -0,0 +1,7 @@
+# Dovecot configuration file
+# Ansible managed: {{ ansible_managed }}
+
+protocols = {{ dovecot_protocols }}
+
+# Dictionary of configuration files
+!include conf.d/*.conf

templates/main.cf.j2

@@ -48,3 +48,21 @@ smtp_tls_security_level = may
 # Other settings
 alias_maps = hash:/etc/aliases
 alias_database = hash:/etc/aliases
+
+# Dovecot Integration
+{% if dovecot_enabled | default(false) %}
+# Use Maildir format
+home_mailbox = Maildir/
+
+{% if dovecot_postfix_sasl_enable | default(false) %}
+# SASL Authentication via Dovecot
+smtpd_sasl_type = dovecot
+smtpd_sasl_path = private/auth
+smtpd_sasl_auth_enable = yes
+{% endif %}
+
+{% if dovecot_postfix_lmtp_enable | default(false) %}
+# Delivery via LMTP
+mailbox_transport = lmtp:unix:private/dovecot-lmtp
+{% endif %}
+{% endif %}