diff --git a/src/platform.js b/src/platform.js
index 28b89bfa5..4046448ef 100644
--- a/src/platform.js
+++ b/src/platform.js
@@ -260,7 +260,7 @@ function createMailConfig(callback) {
             var mailFromValidation = result[settings.MAIL_FROM_VALIDATION_KEY];
 
             if (!safe.fs.writeFileSync(paths.ADDON_CONFIG_DIR + '/mail/mail.ini',
-                `mail_domain=${fqdn}\nmail_server_name=${mailFqdn}\nalerts_from=${alertsFrom}\nalerts_to=${alertsTo}\ncatch_all=${catchAll}\nmail_from_validation=${mailFromValidation}\n`, 'utf8')) {
+                `mail_domains=${fqdn}\nmail_default_domain=${fqdn}\nmail_server_name=${mailFqdn}\nalerts_from=${alertsFrom}\nalerts_to=${alertsTo}\ncatch_all=${catchAll}\nmail_from_validation=${mailFromValidation}\n`, 'utf8')) {
                 return callback(new Error('Could not create mail var file:' + safe.error.message));
             }