added dovecot smtp proxy

example.dovecot.conf

@@ -0,0 +1,43 @@
+# Dovecot SMTP submission proxy configuration (dovecot 2.4 syntax)
+#
+# Terminates SSL/TLS for the local hostname (e.g. smtp.example.com) and
+# proxies every login, credentials included, to the destination server
+# (e.g. smtp.example.net) over its own SSL/TLS. After the login succeeds,
+# dovecot forwards the connection bit-by-bit in both directions.
+
+dovecot_config_version = 2.4.0
+dovecot_storage_version = 2.4.0
+
+protocols = submission
+log_path = /dev/stdout
+
+ssl = yes
+ssl_server_cert_file = /etc/dovecot/ssl/cert.pem
+ssl_server_key_file = /etc/dovecot/ssl/key.pem
+ssl_min_protocol = TLSv1.2
+ssl_client_ca_file = /etc/ssl/certs/ca-certificates.crt
+
+auth_mechanisms = plain login
+
+service submission-login {
+  inet_listener submission {
+    port = 587
+  }
+  inet_listener submissions {
+    port = 465
+    ssl = yes
+  }
+}
+
+# Destination submission server. "ssl = yes" + port 465 = implicit TLS;
+# for a STARTTLS destination use port 587 with "starttls = yes" instead
+# of the ssl field.
+passdb static {
+  fields {
+    nopassword = yes
+    proxy = yes
+    host = smtp.example.net
+    port = 465
+    ssl = yes
+  }
+}