email is optional

smash/web/models/worker.py

@@ -117,7 +117,8 @@ class Worker(models.Model):
                             blank=True
                             )
     email = models.EmailField(
-        verbose_name='E-mail'
+        verbose_name='E-mail',
+        blank=True
     )
 
     specialization = models.CharField(max_length=20,