diff --git a/core/lib/Drupal/Core/Session/AccountInterface.php b/core/lib/Drupal/Core/Session/AccountInterface.php
index 1cf82dcb63..0624f90bb9 100644
--- a/core/lib/Drupal/Core/Session/AccountInterface.php
+++ b/core/lib/Drupal/Core/Session/AccountInterface.php
@@ -146,9 +146,10 @@ public function getAccountName();
   public function getDisplayName();
 
   /**
-   * Returns the email address of this account.
+   * Returns the email address of this account.For anonymous user NULL value is
+   * returned.
    *
-   * @return string
+   * @return string|null
    *   The email address.
    */
   public function getEmail();