Only touch the DB for mailgun if enabled

admin/admin_settings_save.php

@@ -544,8 +544,10 @@ mfh_updateSetting('questionMarkColor', $set['questionMarkColor'], true);
 mfh_updateSetting('dropdownItemTextHoverBackgroundColor', $set['dropdownItemTextHoverBackgroundColor'], true);
 mfh_updateSetting('display_user_agent_information', $set['display_user_agent_information']);
 mfh_updateSetting('navbar_title_url', $set['navbar_title_url'], true);
-mfh_updateSetting('mailgun_api_key', $set['mailgun_api_key'], true);
-mfh_updateSetting('mailgun_domain', $set['mailgun_domain'], true);
+if ($set['use_mailgun'] == 1) {
+    mfh_updateSetting('mailgun_api_key', $set['mailgun_api_key'], true);
+    mfh_updateSetting('mailgun_domain', $set['mailgun_domain'], true);
+}
 mfh_updateSetting('use_mailgun', $set['use_mailgun'], false);
 mfh_updateSetting('enable_calendar', $set['enable_calendar'], false);
 mfh_updateSetting('first_day_of_week', $set['first_day_of_week'], false);