diff --git a/src/apps.js b/src/apps.js
index 3ca568332..361ed45c7 100644
--- a/src/apps.js
+++ b/src/apps.js
@@ -151,7 +151,7 @@ function validatePortBindings(portBindings, manifest) {
         2514, /* cloudron-syslog (lo) */
         config.get('port'), /* app server (lo) */
         constants.SYSADMIN_PORT, /* sysadmin app server (lo) */
-        config.get('smtpPort'), /* internal smtp port (lo) */
+        constants.INTERNAL_SMTP_PORT, /* internal smtp port (lo) */
         config.get('ldapPort'), /* ldap server (lo) */
         3306, /* mysql (lo) */
         4190, /* managesieve */
diff --git a/src/config.js b/src/config.js
index dfa18a7a3..cd3731efd 100644
--- a/src/config.js
+++ b/src/config.js
@@ -85,7 +85,6 @@ function initConfig() {
     data.apiServerOrigin = null;
     data.webServerOrigin = null;
     data.provider = 'generic';
-    data.smtpPort = 2525; // this value comes from mail container
     data.ldapPort = 3002;
     data.dockerProxyPort = 3003;
 
diff --git a/src/constants.js b/src/constants.js
index c6cb3302c..6364bfbdf 100644
--- a/src/constants.js
+++ b/src/constants.js
@@ -21,6 +21,7 @@ exports = module.exports = {
 
     ADMIN_LOCATION: 'my',
 
+    INTERNAL_SMTP_PORT: 2525, // this value comes from the mail container
     SYSADMIN_PORT: 3001,
 
     NGINX_DEFAULT_CONFIG_FILE_NAME: 'default.conf',
diff --git a/src/mailer.js b/src/mailer.js
index 30aae04f7..9e5d9cb13 100644
--- a/src/mailer.js
+++ b/src/mailer.js
@@ -84,7 +84,7 @@ function sendMail(mailOptions, callback) {
 
         var transport = nodemailer.createTransport(smtpTransport({
             host: mailServerIp,
-            port: config.get('smtpPort'),
+            port: constants.INTERNAL_SMTP_PORT,
             auth: {
                 user: mailOptions.authUser || `no-reply@${config.adminDomain()}`,
                 pass: relayToken