diff --git a/CRM/Contact/Form/Task/Label.php b/CRM/Contact/Form/Task/Label.php
index c297cd3a07dd..ba2761e68d56 100644
--- a/CRM/Contact/Form/Task/Label.php
+++ b/CRM/Contact/Form/Task/Label.php
@@ -204,6 +204,7 @@ public function postProcess() {
 
     $messageToken = CRM_Utils_Token::getTokens($mailingFormat);
 
+    // $details[0] is an array of [ contactID => contactDetails ]
     // also get all token values
     CRM_Utils_Hook::tokenValues($details[0],
       $this->_contactIds,
diff --git a/CRM/Contact/Form/Task/LabelCommon.php b/CRM/Contact/Form/Task/LabelCommon.php
index b35673517666..60d344e4bc2c 100644
--- a/CRM/Contact/Form/Task/LabelCommon.php
+++ b/CRM/Contact/Form/Task/LabelCommon.php
@@ -140,6 +140,7 @@ public static function getRows($contactIDs, $locationTypeID, $respectDoNotMail,
     $details = $query->apiQuery($params, $returnProperties, NULL, NULL, 0, $numberofContacts);
 
     $messageToken = CRM_Utils_Token::getTokens($mailingFormat);
+    // $details[0] is an array of [ contactID => contactDetails ]
     $details = $details[0];
     $tokenFields = CRM_Contact_Form_Task_LabelCommon::getTokenData($details);
 
diff --git a/CRM/Mailing/BAO/Mailing.php b/CRM/Mailing/BAO/Mailing.php
index 59c588221cc5..0f5f78ecfa76 100644
--- a/CRM/Mailing/BAO/Mailing.php
+++ b/CRM/Mailing/BAO/Mailing.php
@@ -1080,27 +1080,15 @@ public function compose(
     elseif ($contactId === 0) {
       //anonymous user
       $contact = [];
-      CRM_Utils_Hook::tokenValues($contact, $contactId, $job_id);
+      CRM_Utils_Hook::tokenValues($contact, [$contactId], $job_id);
     }
     else {
       $params = [['contact_id', '=', $contactId, 0, 0]];
       list($contact) = CRM_Contact_BAO_Query::apiQuery($params);
-
-      //CRM-4524
-      $contact = reset($contact);
-
-      if (!$contact || is_a($contact, 'CRM_Core_Error')) {
-        CRM_Core_Error::debug_log_message(ts('CiviMail will not send email to a non-existent contact: %1',
-          [1 => $contactId]
-        ));
-        // setting this because function is called by reference
-        //@todo test not calling function by reference
-        $res = NULL;
-        return $res;
-      }
+      // $contact is an array of [ contactID => contactDetails ]
 
       // also call the hook to get contact details
-      CRM_Utils_Hook::tokenValues($contact, $contactId, $job_id);
+      CRM_Utils_Hook::tokenValues($contact, [$contactId], $job_id);
     }
 
     $pTemplates = $this->getPreparedTemplates();
diff --git a/CRM/Mailing/Page/Preview.php b/CRM/Mailing/Page/Preview.php
index 85daed2ee3a0..6221e1063c34 100644
--- a/CRM/Mailing/Page/Preview.php
+++ b/CRM/Mailing/Page/Preview.php
@@ -66,7 +66,7 @@ public function run() {
       $mailing->getFlattenedTokens(),
       get_class($this)
     );
-
+    // $details[0] is an array of [ contactID => contactDetails ]
     $mime = &$mailing->compose(NULL, NULL, NULL, $session->get('userID'), $fromEmail, $fromEmail,
       TRUE, $details[0][$session->get('userID')], $attachments
     );
diff --git a/CRM/Utils/Hook.php b/CRM/Utils/Hook.php
index 31663cacf55f..58652706fba7 100644
--- a/CRM/Utils/Hook.php
+++ b/CRM/Utils/Hook.php
@@ -854,7 +854,7 @@ public static function alterAdminPanel(&$panels) {
    * tokens returned by the 'tokens' hook
    *
    * @param array $details
-   *   The array to store the token values indexed by contactIDs (unless it a single).
+   *   The array to store the token values indexed by contactIDs.
    * @param array $contactIDs
    *   An array of contactIDs.
    * @param int $jobID
diff --git a/CRM/Utils/Token.php b/CRM/Utils/Token.php
index 156f87a279d7..e1feafa88505 100644
--- a/CRM/Utils/Token.php
+++ b/CRM/Utils/Token.php
@@ -1228,7 +1228,6 @@ public static function getTokenDetails(
     }
 
     $details = CRM_Contact_BAO_Query::apiQuery($params, $returnProperties, NULL, NULL, 0, count($contactIDs), TRUE, FALSE, TRUE, CRM_Contact_BAO_Query::MODE_CONTACTS, NULL, TRUE);
-
     $contactDetails = &$details[0];
 
     foreach ($contactIDs as $contactID) {
@@ -1263,8 +1262,9 @@ public static function getTokenDetails(
       }
     }
 
+    // $contactDetails = &$details[0] = is an array of [ contactID => contactDetails ]
     // also call a hook and get token details
-    CRM_Utils_Hook::tokenValues($details[0],
+    CRM_Utils_Hook::tokenValues($contactDetails,
       $contactIDs,
       $jobID,
       $tokens,
@@ -1291,9 +1291,7 @@ public static function getTokenDetails(
    * @return array
    *   contactDetails with hooks swapped out
    */
-  public static function getAnonymousTokenDetails($contactIDs = [
-    0,
-  ],
+  public static function getAnonymousTokenDetails($contactIDs = [0],
                                            $returnProperties = NULL,
                                            $skipOnHold = TRUE,
                                            $skipDeceased = TRUE,
diff --git a/Civi/Token/TokenCompatSubscriber.php b/Civi/Token/TokenCompatSubscriber.php
index 672080d29ba4..a573337ad96c 100644
--- a/Civi/Token/TokenCompatSubscriber.php
+++ b/Civi/Token/TokenCompatSubscriber.php
@@ -88,12 +88,9 @@ public function onEvaluate(TokenValueEvent $e) {
         $contact = array_merge($contact, $row->context['tmpTokenParams']);
       }
 
-      $contactArray = !is_array($contactId) ? [$contactId => $contact] : $contact;
-
-      // Note: This is a small contract change from the past; data should be missing
-      // less randomly.
+      $contactArray = [$contactId => $contact];
       \CRM_Utils_Hook::tokenValues($contactArray,
-        (array) $contactId,
+        [$contactId],
         empty($row->context['mailingJobId']) ? NULL : $row->context['mailingJobId'],
         $messageTokens,
         $row->context['controller']