[minor] is_ajax check in newsletter
diff --git a/erpnext/support/doctype/newsletter/newsletter.py b/erpnext/support/doctype/newsletter/newsletter.py
index aaf4ddf..57063bb 100644
--- a/erpnext/support/doctype/newsletter/newsletter.py
+++ b/erpnext/support/doctype/newsletter/newsletter.py
@@ -30,7 +30,7 @@
 
 		self.recipients = self.get_recipients()
 
-		if frappe.local.is_ajax:
+		if getattr(frappe.local, "is_ajax", False):
 			# to avoid request timed out!
 			self.validate_send()
 			erpnext.tasks.send_newsletter.delay(frappe.local.site, self.name)