diff --git a/apps/dav/lib/CalDAV/Reminder/INotificationProvider.php b/apps/dav/lib/CalDAV/Reminder/INotificationProvider.php
index feea411e48..69118c67d1 100644
--- a/apps/dav/lib/CalDAV/Reminder/INotificationProvider.php
+++ b/apps/dav/lib/CalDAV/Reminder/INotificationProvider.php
@@ -44,11 +44,11 @@ interface INotificationProvider {
 	 * @param VEvent $vevent
 	 * @param string $calendarDisplayName
 	 * @param IUser[] $users
-	 * @param IUser $userOfReminder
+	 * @param IUser $reminderOwner
 	 * @return void
 	 */
 	public function send(VEvent $vevent,
 						 string $calendarDisplayName,
 						 array $users = [],
-						 IUser $userOfReminder = null): void;
+						 IUser $reminderOwner = null): void;
 }
diff --git a/apps/dav/lib/CalDAV/Reminder/NotificationProvider/AbstractProvider.php b/apps/dav/lib/CalDAV/Reminder/NotificationProvider/AbstractProvider.php
index 8f3df19456..f15688cd21 100644
--- a/apps/dav/lib/CalDAV/Reminder/NotificationProvider/AbstractProvider.php
+++ b/apps/dav/lib/CalDAV/Reminder/NotificationProvider/AbstractProvider.php
@@ -91,13 +91,13 @@ abstract class AbstractProvider implements INotificationProvider {
 	 * @param VEvent $vevent
 	 * @param string $calendarDisplayName
 	 * @param IUser[] $users
-	 * @param IUser $userOfReminder
+	 * @param IUser $reminderOwner
 	 * @return void
 	 */
 	abstract public function send(VEvent $vevent,
 						   string $calendarDisplayName,
 						   array $users = [],
-							IUser $userOfReminder = null): void;
+							IUser $reminderOwner = null): void;
 
 	/**
 	 * @return string
diff --git a/apps/dav/lib/CalDAV/Reminder/NotificationProvider/EmailProvider.php b/apps/dav/lib/CalDAV/Reminder/NotificationProvider/EmailProvider.php
index 371a4bd876..056b633dc6 100644
--- a/apps/dav/lib/CalDAV/Reminder/NotificationProvider/EmailProvider.php
+++ b/apps/dav/lib/CalDAV/Reminder/NotificationProvider/EmailProvider.php
@@ -81,13 +81,13 @@ class EmailProvider extends AbstractProvider {
 	 * @param VEvent $vevent
 	 * @param string $calendarDisplayName
 	 * @param array $users
-	 * @param IUser $userOfReminder
+	 * @param IUser $reminderOwner
 	 * @throws \Exception
 	 */
 	public function send(VEvent $vevent,
 						 string $calendarDisplayName,
 						 array $users = [],
-						 IUser $userOfReminder = null):void {
+						 IUser $reminderOwner = null):void {
 		$fallbackLanguage = $this->getFallbackLanguage();
 
 		$emailAddressesOfSharees = $this->getEMailAddressesOfAllUsersWithWriteAccessToCalendar($users);
@@ -96,7 +96,7 @@ class EmailProvider extends AbstractProvider {
 
 		$emailAddressesOfAttendees = [];
 
-		if ($userOfReminder && strcasecmp($userOfReminder->getEMailAddress(), key($organizer)) == 0) {
+		if ($organizer !== null && $reminderOwner instanceof IUser && strcasecmp($reminderOwner->getEMailAddress(), key($organizer)) === 0) {
 			$emailAddressesOfAttendees = $this->getAllEMailAddressesFromEvent($vevent);
 		}
 
@@ -205,7 +205,7 @@ class EmailProvider extends AbstractProvider {
 		}
 
 		$organizer = $vevent->ORGANIZER;
-		if (!str_starts_with($organizer->getValue(), 'mailto:')) {
+		if (strcasecmp($organizer->getValue(), 'mailto:') !== 0) {
 			return null;
 		}
 
diff --git a/apps/dav/lib/CalDAV/Reminder/NotificationProvider/PushProvider.php b/apps/dav/lib/CalDAV/Reminder/NotificationProvider/PushProvider.php
index 67b08929fa..72c39cc904 100644
--- a/apps/dav/lib/CalDAV/Reminder/NotificationProvider/PushProvider.php
+++ b/apps/dav/lib/CalDAV/Reminder/NotificationProvider/PushProvider.php
@@ -83,13 +83,13 @@ class PushProvider extends AbstractProvider {
 	 * @param VEvent $vevent
 	 * @param string $calendarDisplayName
 	 * @param IUser[] $users
-	 * @param IUser $userOfReminder
+	 * @param IUser $reminderOwner
 	 * @throws \Exception
 	 */
 	public function send(VEvent $vevent,
 						 string $calendarDisplayName = null,
 						 array $users = [],
-						 IUser $userOfReminder = null):void {
+						 IUser $reminderOwner = null):void {
 		if ($this->config->getAppValue('dav', 'sendEventRemindersPush', 'no') !== 'yes') {
 			return;
 		}