validate email id only if provided (#9020)

diff --git a/erpnext/hr/doctype/job_applicant/job_applicant.py b/erpnext/hr/doctype/job_applicant/job_applicant.py
index acc1c64..2de20dd 100644
--- a/erpnext/hr/doctype/job_applicant/job_applicant.py
+++ b/erpnext/hr/doctype/job_applicant/job_applicant.py
@@ -27,7 +27,8 @@
 
 	def validate(self):
 		self.check_email_id_is_unique()
-		validate_email_add(self.email_id, True)
+		if self.email_id:
+			validate_email_add(self.email_id, True)
 
 		if not self.applicant_name and self.email_id:
 			guess = self.email_id.split('@')[0]