added EMailField for validation

input/models.py

@@ -7,7 +7,7 @@ from .settings import ACCOUNTS
 
 class Volunteer(models.Model):
     realname = models.CharField(max_length=200, null=True, verbose_name="Name / Hauptansprechperson")
-    email = models.CharField(max_length=200, null=True, verbose_name='E-Mail-Adresse')
+    email = models.EmailField(max_length=200, null=True, verbose_name='E-Mail-Adresse')
 
     # the following Fields are not supposed to be edited by users
     granted = models.BooleanField(null=True)