diff --git a/imaginaerraum_door_admin/webapp.py b/imaginaerraum_door_admin/webapp.py
index cbaf43a..af44cfb 100644
--- a/imaginaerraum_door_admin/webapp.py
+++ b/imaginaerraum_door_admin/webapp.py
@@ -12,7 +12,7 @@ from flask_security.models import fsqla_v2 as fsqla
 from flask_security.forms import LoginForm, Required, PasswordField
 from flask_security.utils import find_user, verify_password
 from flask_mail import Mail
-from email_validator import validate_email
+from email_validator import validate_email, EmailNotValidError
 
 import json
 import secrets
@@ -146,7 +146,7 @@ def create_application(config):
     ldap_server = ldap3.Server(config.ldap_url)
     local_ldap_cache = {}  # dict for caching LDAP authorization locally (stores username + hashed password)
 
-    def validate_ldap(user, password):
+    def validate_ldap(username, password):
         """Validate the user and password through an LDAP server.
 
         If the connection completes successfully the given user and password is authorized and the password is stored
@@ -165,7 +165,7 @@ def create_application(config):
         """
 
         try:
-            con = ldap3.Connection(ldap_server, user="uid=%s,ou=Users,dc=imaginaerraum,dc=de" % (user.username,),
+            con = ldap3.Connection(ldap_server, user=f"uid={username},ou=Users,dc=imaginaerraum,dc=de",
                                    password=password, auto_bind=True)
         except ldap3.core.exceptions.LDAPBindError:
             # server reachable but user unauthorized -> fail
@@ -173,11 +173,14 @@ def create_application(config):
         except LDAPSocketOpenError:
             # server not reachable -> try cached authorization data
             return user.username in local_ldap_cache and verify_password(password, local_ldap_cache[user.username])
-        except Exception:
+        except Exception as e:
             # for other Exceptions we just fail
             return False
 
         # TODO check if user has permission to edit tokens
+        lock_permission = con.search('ou=Users,dc=imaginaerraum,dc=de', f'(&(uid={user.username})(memberof=cn=Members,ou=Groups,dc=imaginaerraum,dc=de))')
+        token_granting_permission = con.search('ou=Users,dc=imaginaerraum,dc=de',
+                            f'(&(uid={user.username})(memberof=cn=Vorstand,ou=Groups,dc=imaginaerraum,dc=de))')
         # if LDAP authorization succeeds we cache the password locally (in memory) to allow LDAP authentication even if
         # the server is not reachable
         local_ldap_cache[user.username] = hash_password(password)
@@ -188,17 +191,32 @@ def create_application(config):
         password = PasswordField('Passwort', [Required()])
 
         def validate(self):
-            # try authorizing locally using Flask security user datastore
-            authorized = super(ExtendedLoginForm, self).validate()
+            # try authorizing using LDAP
+            # authorization in LDAP uses username -> get username associated with email from the database
+            try:
+                # if an email (instead of a username) was entered for authentication we check if there already is a user
+                # with that email in the database
+                validate_email(self.email.data)
+                user = find_user(self.email.data)
+                if user is not None:
+                    username = user.username
+                else:
+                    # this means there is no user with that email in the database
+                    username = None
+            except EmailNotValidError:
+                # else we use the entered credentials as username
+                username = self.email.data
+
+            authorized = validate_ldap(username, self.password.data)
+
+            if authorized:
+                logger.info(f"Admin user with credentials '{self.email.data}' authorized through LDAP")
 
             if not authorized:
-                # try authorizing using LDAP
-                # authorization in LDAP uses username -> get username associated with email from the database
-                user = find_user(self.email.data)
-                authorized = validate_ldap(user, self.password.data)
-                if authorized:
-                    logger.info(f"Admin user with credentials '{self.email.data}' authorized through LDAP")
-            else:
+                # try authorizing locally using Flask security user datastore
+                authorized = super(ExtendedLoginForm, self).validate()
+
+            if authorized:
                 logger.info(f"Admin user with credentials '{self.email.data}' authorized through local database")
 
             # if any of the authorization methods is successful we authorize the user