diff --git a/lib/MailQueueHandler.php b/lib/MailQueueHandler.php
index 22039c3a7..5e64a5b79 100644
--- a/lib/MailQueueHandler.php
+++ b/lib/MailQueueHandler.php
@@ -325,6 +325,11 @@ protected function sendEmailToUser($userName, $email, $lang, $timezone, $maxTime
 			return true;
 		}
 
+		if (!$this->mailer->validateMailAddress($email)) {
+			$this->logger->warning('Notification for user "{user}" not sent because the email address "{email}" is invalid.', ['user' => $userName, 'email' => $email]);
+			return true;
+		}
+
 		list($mailData, $skippedCount) = $this->getItemsForUser($userName, $maxTime);
 
 		$l = $this->getLanguage($lang);
diff --git a/tests/MailQueueHandlerTest.php b/tests/MailQueueHandlerTest.php
index a8446323c..0638eba70 100644
--- a/tests/MailQueueHandlerTest.php
+++ b/tests/MailQueueHandlerTest.php
@@ -242,6 +242,10 @@ public function testSendEmailToUser() {
 		$this->mailer->expects($this->once())
 			->method('createEMailTemplate')
 			->willReturn($template);
+		$this->mailer->expects($this->once())
+			->method('validateMailAddress')
+			->with($email)
+			->willReturn(true);
 
 		$template->expects($this->once())
 			->method('addHeader');