diff --git a/modules/backend/classes/FormField.php b/modules/backend/classes/FormField.php
index 1e3a1ca49..ad3bdacf0 100644
--- a/modules/backend/classes/FormField.php
+++ b/modules/backend/classes/FormField.php
@@ -149,6 +149,11 @@ class FormField
      */
     public $dependsOn;
 
+    /**
+     * @var array Other field names this field can be triggered by, see the Trigger API documentation.
+     */
+    public $trigger;
+
     /**
      * Constructor.
      * @param string $fieldName
@@ -278,6 +283,9 @@ class FormField
         if (isset($config['dependsOn'])) {
             $this->dependsOn = $config['dependsOn'];
         }
+        if (isset($config['trigger'])) {
+            $this->trigger = $config['trigger'];
+        }
         if (isset($config['path'])) {
             $this->path = $config['path'];
         }
@@ -352,9 +360,51 @@ class FormField
     public function getAttributes($position = 'field', $htmlBuild = true)
     {
         $result = array_get($this->attributes, $position, []);
+        $result = $this->filterAttributes($result, $position);
         return $htmlBuild ? Html::attributes($result) : $result;
     }
 
+    /**
+     * Adds any circumstantial attributes to the field based on other
+     * settings, such as the 'trigger' option.
+     * @param  array $attributes
+     * @param  string $position
+     * @return array
+     */
+    protected function filterAttributes($attributes, $position = 'field')
+    {
+        if (!$this->trigger || !is_array($this->trigger))
+            return $attributes;
+
+        $triggerAction = array_get($this->trigger, 'action');
+        $triggerField = array_get($this->trigger, 'field');
+        $triggerCondition = array_get($this->trigger, 'condition');
+
+        // Apply these to container
+        if (in_array($triggerAction, ['hide', 'show']) && $position != 'container')
+            return $attributes;
+
+        // Apply these to field/input
+        if (in_array($triggerAction, ['enable', 'disable', 'empty']) && $position != 'field')
+            return $attributes;
+
+        if ($this->arrayName) {
+            $fullTriggerField = $this->arrayName.'['.implode('][', Str::evalHtmlArray($triggerField)).']';
+        }
+        else {
+            $fullTriggerField = $triggerField;
+        }
+
+        $newAttributes = [
+            'data-trigger' => '[name="'.$fullTriggerField.'"]',
+            'data-trigger-action' => $triggerAction,
+            'data-trigger-condition' => $triggerCondition
+        ];
+
+        $attributes = $attributes + $newAttributes;
+        return $attributes;
+    }
+
     /**
      * Returns a value suitable for the field name property.
      * @param  string $arrayName Specify a custom array name
diff --git a/modules/system/models/mailsettings/fields.yaml b/modules/system/models/mailsettings/fields.yaml
index 763eb65c3..c38ecf280 100644
--- a/modules/system/models/mailsettings/fields.yaml
+++ b/modules/system/models/mailsettings/fields.yaml
@@ -3,68 +3,108 @@
 # ===================================
 
 tabs:
-  fields:
+    fields:
 
-    send_mode:
-      label: system::lang.mail.method
-      type: dropdown
-      tab: system::lang.mail.general
+        sender_name:
+            label: system::lang.mail.sender_name
+            span: auto
+            tab: system::lang.mail.general
 
-    sender_name:
-      label: system::lang.mail.sender_name
-      span: auto
-      tab: system::lang.mail.general
+        sender_email:
+            label: system::lang.mail.sender_email
+            span: auto
+            tab: system::lang.mail.general
 
-    sender_email:
-      label: system::lang.mail.sender_email
-      span: auto
-      tab: system::lang.mail.general
+        send_mode:
+            label: system::lang.mail.method
+            type: dropdown
+            tab: system::lang.mail.general
 
-    smtp_address:
-      label: system::lang.mail.smtp_address
-      tab: system::lang.mail.smtp
+        smtp_address:
+            label: system::lang.mail.smtp_address
+            tab: system::lang.mail.general
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[smtp]
 
-    smtp_authorization:
-      type: checkbox
-      label: system::lang.mail.smtp_authorization
-      tab: system::lang.mail.smtp
-      comment: system::lang.mail.smtp_authorization_comment
+        smtp_authorization:
+            type: checkbox
+            label: system::lang.mail.smtp_authorization
+            tab: system::lang.mail.general
+            comment: system::lang.mail.smtp_authorization_comment
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[smtp]
 
-    smtp_user:
-      label: system::lang.mail.smtp_username
-      tab: system::lang.mail.smtp
-      span: left
+        smtp_user:
+            label: system::lang.mail.smtp_username
+            tab: system::lang.mail.general
+            span: left
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[smtp]
 
-    smtp_password:
-      label: system::lang.mail.smtp_password
-      tab: system::lang.mail.smtp
-      span: right
+        smtp_password:
+            label: system::lang.mail.smtp_password
+            tab: system::lang.mail.general
+            span: right
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[smtp]
 
-    smtp_port:
-      label: system::lang.mail.smtp_port
-      tab: system::lang.mail.smtp
+        smtp_port:
+            label: system::lang.mail.smtp_port
+            tab: system::lang.mail.general
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[smtp]
 
-    smtp_ssl:
-      type: checkbox
-      label: system::lang.mail.smtp_ssl
-      tab: system::lang.mail.smtp
+        smtp_ssl:
+            type: checkbox
+            label: system::lang.mail.smtp_ssl
+            tab: system::lang.mail.general
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[smtp]
 
-    sendmail_path:
-      label: system::lang.mail.sendmail_path
-      commentAbove: system::lang.mail.sendmail_path_comment
-      tab: system::lang.mail.sendmail
+        sendmail_path:
+            label: system::lang.mail.sendmail_path
+            commentAbove: system::lang.mail.sendmail_path_comment
+            tab: system::lang.mail.general
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[sendmail]
 
-    mailgun_domain:
-      label: system::lang.mail.mailgun_domain
-      commentAbove: system::lang.mail.mailgun_domain_comment
-      tab: system::lang.mail.mailgun
+        mailgun_domain:
+            label: system::lang.mail.mailgun_domain
+            commentAbove: system::lang.mail.mailgun_domain_comment
+            tab: system::lang.mail.general
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[mailgun]
 
-    mailgun_secret:
-      label: system::lang.mail.mailgun_secret
-      commentAbove: system::lang.mail.mailgun_secret_comment
-      tab: system::lang.mail.mailgun
-      
-    mandrill_secret:
-      label: system::lang.mail.mandrill_secret
-      commentAbove: system::lang.mail.mandrill_secret_comment
-      tab: system::lang.mail.mandrill
+        mailgun_secret:
+            label: system::lang.mail.mailgun_secret
+            commentAbove: system::lang.mail.mailgun_secret_comment
+            tab: system::lang.mail.general
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[mailgun]
+
+        mandrill_secret:
+            label: system::lang.mail.mandrill_secret
+            commentAbove: system::lang.mail.mandrill_secret_comment
+            tab: system::lang.mail.general
+            trigger:
+                action: show
+                field: send_mode
+                condition: value[mandrill]