SiteEmailAddress - Enforce default one default per domain

Also removed unnecessary domain filtering logic from OptionValue as this was the only option group it applied to.

CRM/Core/BAO/OptionValue.php

@@ -551,11 +551,6 @@ class CRM_Core_BAO_OptionValue extends CRM_Core_DAO_OptionValue implements \Civi
     $query = 'UPDATE civicrm_option_value SET is_default = 0 WHERE option_group_id = %1 AND id <> %2';
     $queryParams = [1 => [$optionGroupID, 'Integer'], 2 => [$id, 'Integer']];
 
-    // Limit update by domain of option. This is loaded if it is a domain option group.
-    if (!empty($optionValue->domain_id)) {
-      $query .= ' AND domain_id = %3';
-      $queryParams[3] = [(int) $optionValue->domain_id, 'Integer'];
-    }
     if (in_array($groupName, ['email_greeting', 'postal_greeting', 'addressee'], TRUE)) {
       $variableNumber = count($queryParams) + 1;
       $query .= ' AND filter = %' . $variableNumber;

CRM/Core/BAO/SiteEmailAddress.php

+<?php
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+/**
+ *
+ * @package CRM
+ * @copyright CiviCRM LLC https://civicrm.org/licensing
+ */
+
+/**
+ * SiteEmailAddress business logic
+ */
+class CRM_Core_BAO_SiteEmailAddress extends CRM_Core_DAO_SiteEmailAddress implements \Civi\Core\HookInterface {
+
+  public static function self_hook_civicrm_pre(\Civi\Core\Event\PreEvent $event) {
+    // When setting default, ensure other records for this domain are not the default
+    if (($event->action === 'create' || $event->action === 'edit') && !empty($event->params['is_default'])) {
+      $domainId = $event->params['domain_id'] ?? self::getDbVal('domain_id', $event->id);
+      CRM_Core_DAO::executeQuery('UPDATE civicrm_site_email_address SET is_default = 0 WHERE domain_id = %1 AND is_default = 1', [
+        1 => [$domainId, 'Positive'],
+      ]);
+    }
+  }
+
+}