diff --git a/CHANGES b/CHANGES
index c353eb738..970d12d33 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1582,4 +1582,5 @@
 * Show app upstream version in the info dialog
 * Add Scaleway ObjectStorage backup backend
 * Preserve update backups for 3 weeks
+* Make send test mail functionality work with secondary domain
 
diff --git a/src/mailer.js b/src/mailer.js
index fcda14a01..697c642c1 100644
--- a/src/mailer.js
+++ b/src/mailer.js
@@ -85,7 +85,7 @@ function sendMail(mailOptions, callback) {
             host: mailServerIp,
             port: config.get('smtpPort'),
             auth: {
-                user: `no-reply@${config.adminDomain()}`,
+                user: mailOptions.authUser || `no-reply@${config.adminDomain()}`,
                 pass: relayToken
             }
         }));
@@ -432,6 +432,7 @@ function sendTestMail(domain, email, callback) {
         if (error) return debug('Error getting mail details:', error);
 
         var mailOptions = {
+            authUser: `no-reply@${domain}`,
             from: `"${mailConfig.cloudronName}" <no-reply@${domain}>`,
             to: email,
             subject: util.format('Test Email from %s', mailConfig.cloudronName),