feat: add SMTP submission listener and enhance stalwart configuration

- add SMTP submission listener on port 587 with TLS requirement
- configure HAProxy frontend/backend for submission with send-proxy-v2 support
- add send-proxy-v2 support to all listeners
- add dynamic HAProxy node discovery for proxy trusted networks
- use service hostname instead of node FQDN for autoconfig/autodiscover
- remove redundant IMAP/IMAPS/SMTP alt-names from TLS certificates
- update VRRP CNAME configuration to use mail.main.unkin.net

site/profiles/manifests/stalwart/haproxy.pp

@@ -15,6 +15,7 @@ class profiles::stalwart::haproxy (
       'inter 2s',
       'rise 3',
       'fall 2',
+      'send-proxy-v2',
     ]
   }
 
@@ -27,6 +28,7 @@ class profiles::stalwart::haproxy (
       'inter 3s',
       'rise 2',
       'fall 3',
+      'send-proxy-v2',
     ]
   }
 
@@ -41,6 +43,7 @@ class profiles::stalwart::haproxy (
       'inter 3s',
       'rise 2',
       'fall 3',
+      'send-proxy-v2',
     ]
   }
 
@@ -53,6 +56,20 @@ class profiles::stalwart::haproxy (
       'inter 3s',
       'rise 2',
       'fall 3',
+      'send-proxy-v2',
+    ]
+  }
+
+  # smtp submission
+  profiles::haproxy::balancemember { "${facts['networking']['fqdn']}_587":
+    service => 'be_stalwart_submission',
+    ports   => [587],
+    options => [
+      'check',
+      'inter 3s',
+      'rise 2',
+      'fall 3',
+      'send-proxy-v2',
     ]
   }