diff --git a/js/src/admin/components/MailPage.js b/js/src/admin/components/MailPage.js
index 442e513d5..6a7b41e62 100644
--- a/js/src/admin/components/MailPage.js
+++ b/js/src/admin/components/MailPage.js
@@ -29,12 +29,13 @@ export default class MailPage extends Page {
         {}
       );
 
-      Object.keys(this.driverFields).flatMap(key => this.driverFields[key]).forEach(
-        key => {
-          this.fields.push(key);
-          this.values[key] = m.prop(settings[key]);
+      for (const driver in this.driverFields) {
+        for (const field in this.driverFields[driver]) {
+          this.fields.push(field);
+          this.values[field] = m.prop(settings[field]);
         }
-      );
+      }
+
       this.loading = false;
       m.redraw();
     });
@@ -87,9 +88,9 @@ export default class MailPage extends Page {
               className: 'MailPage-MailSettings',
               children: [
                 <div className="MailPage-MailSettings-input">
-                  {this.driverFields[this.values.mail_driver()].flatMap(field => [
+                  {Object.keys(this.driverFields[this.values.mail_driver()]).map(field => [
                     <label>{app.translator.trans(`core.admin.email.${field}_label`)}</label>,
-                    <input className="FormControl" value={this.values[field]() || ''} oninput={m.withAttr('value', this.values[field])} />
+                    this.renderField(field),
                   ])}
                 </div>
               ]
@@ -108,6 +109,18 @@ export default class MailPage extends Page {
     );
   }
 
+  renderField(name) {
+    const driver = this.values.mail_driver();
+    const field = this.driverFields[driver][name];
+    const prop = this.values[name];
+
+    if (typeof field === 'string') {
+      return <input className="FormControl" value={prop() || ''} oninput={m.withAttr('value', prop)}/>;
+    } else {
+      return <Select value={prop()} options={field} onchange={prop} />;
+    }
+  }
+
   changed() {
     return this.fields.some(key => this.values[key]() !== app.data.settings[key]);
   }
diff --git a/src/Mail/MailgunDriver.php b/src/Mail/MailgunDriver.php
index 1ccbb96fd..d600db6b4 100644
--- a/src/Mail/MailgunDriver.php
+++ b/src/Mail/MailgunDriver.php
@@ -19,8 +19,12 @@ class MailgunDriver implements DriverInterface
     public function availableSettings(): array
     {
         return [
-            'mail_mailgun_secret', // the secret key
-            'mail_mailgun_domain', // the API base URL
+            'mail_mailgun_secret' => '', // the secret key
+            'mail_mailgun_domain' => '', // the API base URL
+            'mail_mailgun_region' => [ // region's endpoint
+                'api.mailgun.net' => 'US',
+                'api.eu.mailgun.net' => 'EU',
+            ],
         ];
     }
 
@@ -29,7 +33,8 @@ class MailgunDriver implements DriverInterface
         return new MailgunTransport(
             new Client(['connect_timeout' => 60]),
             $settings->get('mail_mailgun_secret'),
-            $settings->get('mail_mailgun_domain')
+            $settings->get('mail_mailgun_domain'),
+            $settings->get('mail_mailgun_region')
         );
     }
 }
diff --git a/src/Mail/MandrillDriver.php b/src/Mail/MandrillDriver.php
index 7cbaa7480..45a0c4051 100644
--- a/src/Mail/MandrillDriver.php
+++ b/src/Mail/MandrillDriver.php
@@ -19,7 +19,7 @@ class MandrillDriver implements DriverInterface
     public function availableSettings(): array
     {
         return [
-            'mail_mandrill_secret',
+            'mail_mandrill_secret' => '',
         ];
     }
 
diff --git a/src/Mail/SesDriver.php b/src/Mail/SesDriver.php
index 774ad56a0..8248bab0e 100644
--- a/src/Mail/SesDriver.php
+++ b/src/Mail/SesDriver.php
@@ -19,9 +19,9 @@ class SesDriver implements DriverInterface
     public function availableSettings(): array
     {
         return [
-            'mail_ses_key',
-            'mail_ses_secret',
-            'mail_ses_region',
+            'mail_ses_key' => '',
+            'mail_ses_secret' => '',
+            'mail_ses_region' => '',
         ];
     }
 
diff --git a/src/Mail/SmtpDriver.php b/src/Mail/SmtpDriver.php
index ae3ebdc39..b6233cfe8 100644
--- a/src/Mail/SmtpDriver.php
+++ b/src/Mail/SmtpDriver.php
@@ -18,11 +18,11 @@ class SmtpDriver implements DriverInterface
     public function availableSettings(): array
     {
         return [
-            'mail_host', // a hostname, IPv4 address or IPv6 wrapped in []
-            'mail_port', // a number, defaults to 25
-            'mail_encryption', // "tls" or "ssl"
-            'mail_username', // required
-            'mail_password', // required
+            'mail_host' => '', // a hostname, IPv4 address or IPv6 wrapped in []
+            'mail_port' => '', // a number, defaults to 25
+            'mail_encryption' => '', // "tls" or "ssl"
+            'mail_username' => '', // required
+            'mail_password' => '', // required
         ];
     }