diff --git a/lib/Listener/UserChangedListener.php b/lib/Listener/UserChangedListener.php
index 48c432ca..f3b7ef1f 100644
--- a/lib/Listener/UserChangedListener.php
+++ b/lib/Listener/UserChangedListener.php
@@ -11,6 +11,7 @@
 use OCA\Guests\GuestManager;
 use OCP\EventDispatcher\Event;
 use OCP\EventDispatcher\IEventListener;
+use OCP\IAppConfig;
 use OCP\IUserSession;
 use OCP\User\Events\UserChangedEvent;
 
@@ -23,6 +24,7 @@ class UserChangedListener implements IEventListener {
 	public function __construct(
 		private readonly IUserSession $userSession,
 		private readonly GuestManager $guestManager,
+		private readonly IAppConfig $appConfig,
 	) {
 	}
 
@@ -43,6 +45,10 @@ public function handle(Event $event): void {
 		if (strtolower($event->getValue()) === strtolower($user->getUID())) {
 			return;
 		}
+		if ($this->appConfig->getValueBool('guests', 'allow_email_change', false, true)) {
+			return;
+		}
+
 		$user->setSystemEMailAddress(strtolower($user->getUID()));
 		$event->stopPropagation();
 	}
diff --git a/lib/Repair/ResetEmails.php b/lib/Repair/ResetEmails.php
index 5c5b9e93..7f1521f2 100644
--- a/lib/Repair/ResetEmails.php
+++ b/lib/Repair/ResetEmails.php
@@ -9,6 +9,7 @@
 namespace OCA\Guests\Repair;
 
 use OCA\Guests\GuestManager;
+use OCP\IAppConfig;
 use OCP\IConfig;
 use OCP\IUserManager;
 use OCP\Migration\IOutput;
@@ -18,6 +19,7 @@ class ResetEmails implements IRepairStep {
 	public function __construct(
 		private readonly GuestManager $guestManager,
 		private readonly IUserManager $userManager,
+		private readonly IAppConfig $appConfig,
 		private readonly IConfig $config,
 	) {
 	}
@@ -30,6 +32,10 @@ public function getName(): string {
 	 * @return void
 	 */
 	public function run(IOutput $output) {
+		if ($this->appConfig->getValueBool('guests', 'allow_email_change', false, true)) {
+			return;
+		}
+
 		foreach ($this->guestManager->listGuests() as $guestId) {
 			$guest = $this->userManager->get($guestId);
 			if (strtolower($guest?->getSystemEMailAddress() ?? '') !== strtolower($guestId)) {