diff --git a/extension.json b/extension.json
index 793ce6b..6c34a64 100644
--- a/extension.json
+++ b/extension.json
@@ -34,10 +34,15 @@
     "DefaultOptions": {
       "class": "MediaWiki\\Extension\\UnifiedExtensionForFemiwiki\\HookHandlers\\DefaultOptions",
       "services": ["MainConfig", "UserOptionsManager"]
+    },
+    "SpamEmail": {
+      "class": "MediaWiki\\Extension\\UnifiedExtensionForFemiwiki\\HookHandlers\\SpamEmail",
+      "services": ["MainConfig", "DBLoadBalancer", "DatabaseBlockStore"]
     }
   },
   "Hooks": {
     "HtmlPageLinkRendererBegin": "main",
+    "isValidEmailAddr": "SpamEmail",
     "LinkerMakeExternalLink": "main",
     "OutputPageParserOutput": "RelatedArticles",
     "SidebarBeforeOutput": "main",
@@ -63,6 +68,10 @@
     "UnifiedExtensionForFemiwikiRelatedArticlesTargetNamespaces": {
       "value": [],
       "description": "An array of namespaces which can be a target for RelatedArticles. Empty array means allowing all namespaces."
+    },
+    "UnifiedExtensionForFemiwikiBlockByEmail": {
+      "value": true,
+      "description": "Block emails used by block users"
     }
   },
   "TestAutoloadNamespaces": {
diff --git a/includes/HookHandlers/SpamEmail.php b/includes/HookHandlers/SpamEmail.php
new file mode 100644
index 0000000..549a04d
--- /dev/null
+++ b/includes/HookHandlers/SpamEmail.php
@@ -0,0 +1,80 @@
+<?php
+
+namespace MediaWiki\Extension\UnifiedExtensionForFemiwiki\HookHandlers;
+
+use Config;
+use MediaWiki\Block\DatabaseBlockStore;
+use MediaWiki\Extension\SpamBlacklist\BaseBlacklist;
+use MediaWiki\User\User;
+use Wikimedia\AtEase\AtEase;
+use Wikimedia\Rdbms\ILoadBalancer;
+
+class SpamEmail implements
+	\MediaWiki\Hook\IsValidEmailAddrHook
+	{
+
+	/** @var Config */
+	private $config;
+
+	/** @var ILoadBalancer */
+	private $loadBalancer;
+
+	/** @var DatabaseBlockStore */
+	private $databaseBlockStore;
+
+	/**
+	 * @param Config $config
+	 * @param ILoadBalancer $loadBalancer
+	 * @param DatabaseBlockStore $databaseBlockStore
+	 */
+	public function __construct(
+		Config $config,
+		ILoadBalancer $loadBalancer,
+		DatabaseBlockStore $databaseBlockStore
+		) {
+		$this->config = $config;
+		$this->loadBalancer = $loadBalancer;
+		$this->databaseBlockStore = $databaseBlockStore;
+	}
+
+	/** @inheritDoc */
+	public function onIsValidEmailAddr( $addr, &$result ) {
+		if ( !$this->config->get( 'UnifiedExtensionForFemiwikiBlockByEmail' ) ) {
+			return true;
+		}
+
+		// Check againt MediaWiki:Email-blacklist
+		$denylist = BaseBlacklist::getEmailBlacklist()->getBlacklists();
+		foreach ( $denylist as $regex ) {
+			AtEase::suppressWarnings();
+			$match = preg_match( $regex, $addr );
+			AtEase::restoreWarnings();
+			if ( $match ) {
+				return false;
+			}
+		}
+
+		// Check email addresses of block users
+		if ( version_compare( '1.42', MW_VERSION, '<=' ) ) {
+			$emails = array_filter( array_unique( array_map(
+				$this->databaseBlockStore->newListFromConds( [ 'bt_user IS NOT NULL' ] ),
+				static fn( $block ) => User::newFromIdentity( $block->getBlocker() )->getEmail()
+			) ) );
+		} else {
+			$dbr = $this->loadBalancer->getConnectionRef( ILoadBalancer::DB_REPLICA );
+			$emails = $dbr->newSelectQueryBuilder()
+				->fields( [ 'user_email' ] )
+				->tables( [ 'ipblocks' ] )
+				->join( 'user', 'user_id = ipb_user' )
+				->conds( [
+					'ipb_user IS NOT NULL',
+					"ipb_expiry > " . $dbr->addQuotes( $dbr->timestamp() ),
+				] )
+				->fetchFieldValues();
+			$emails = array_filter(array_unique($emails));
+		}
+		if ( in_array( $addr, $emails ) ) {
+			return false;
+		}
+	}
+}