diff --git a/src/apps.js b/src/apps.js
index be8d92671..40b191d96 100644
--- a/src/apps.js
+++ b/src/apps.js
@@ -137,6 +137,7 @@ function validatePortBindings(portBindings, tcpPorts) {
         2020, /* install server */
         config.get('port'), /* app server (lo) */
         config.get('sysadminPort'), /* sysadmin app server (lo) */
+        config.get('smtpPort'), /* internal smtp port (lo) */
         config.get('ldapPort'), /* ldap server (lo) */
         config.get('oauthProxyPort'), /* oauth proxy server (lo) */
         config.get('simpleAuthPort'), /* simple auth server (lo) */
diff --git a/src/config.js b/src/config.js
index 83b05a35d..7935e90c4 100644
--- a/src/config.js
+++ b/src/config.js
@@ -79,6 +79,7 @@ function initConfig() {
     data.version = null;
     data.isCustomDomain = false;
     data.webServerOrigin = null;
+    data.smtpPort = 2525; // // this value comes from mail container
     data.sysadminPort = 3001;
     data.ldapPort = 3002;
     data.oauthProxyPort = 3003;
diff --git a/src/mailer.js b/src/mailer.js
index 6a32d8375..2c760636c 100644
--- a/src/mailer.js
+++ b/src/mailer.js
@@ -159,7 +159,7 @@ function sendMails(queue) {
 
         var transport = nodemailer.createTransport(smtpTransport({
             host: mailServerIp,
-            port: 2525, // this value comes from mail container
+            port: config.get('smtpPort'),
             auth: {
                 user: 'no-reply', // derive from adminEmail
                 pass: 'supersecret'