proxmox-backup: set mail relay

roles/proxmox-backup/handlers/main.yml

@@ -16,3 +16,9 @@
     name: nftables
     state: reloaded
   when: "'handler' not in ansible_skip_tags"
+
+- name: reload postfix
+  service:
+    name: postfix
+    state: reloaded
+  when: "'handler' not in ansible_skip_tags"

roles/proxmox-backup/tasks/main.yml

@@ -93,4 +93,11 @@
              | map(attribute="ip_addresses") | flatten | map(attribute="dns_name") | first }}'
   changed_when: false # maybe write a proper check if certificate requests are ever ansibled
 
+- name: Set SMTP relay
+  lineinfile:
+    path: /etc/postfix/main.cf
+    regexp: '^relayhost ='
+    line: 'relayhost = {{ mail_relay | default("") }}'
+  notify: reload postfix
+
 - include_tasks: firewall.yml