add global option DIGEST_ENABLE

config.php-dist

@@ -134,6 +134,9 @@
 	define('USE_CURL_FOR_ICONS', false);
 	// Fetch favicons using CURL, useful if your PHP has disabled remote fopen()
 
+	define('DIGEST_ENABLE', true);
+	// Global option to enable daily digests
+
 	define('DIGEST_HOSTNAME', 'some.ttrss.host.dom');
 	// Hostname for email digest signature
 

functions.php

@@ -2380,6 +2380,8 @@
 
 	function send_headlines_digests($link, $limit = 100) {
 
+		if (!DIGEST_ENABLE) return false;
+
 		$user_limit = DIGEST_EMAIL_LIMIT;
 		$days = DIGEST_DAYS_BACK;