We create the funciton that validates an email address checking if the token if correct.

app/authentification/utils.py

@@ -0,0 +1,21 @@
+from django.shortcuts import render
+from django.shortcuts import redirect
+from django.contrib.auth import login
+from django.utils.encoding import force_text
+from django.utils.http import urlsafe_base64_decode
+from .tokens import account_activation_token
+from django.contrib.auth.models import User
+
+def activate(request, uidb64, token):
+    try:
+        uid = force_text(urlsafe_base64_decode(uidb64))
+        user = User.objects.get(pk=uid)
+    except(TypeError, ValueError, OverflowError, User.DoesNotExist):
+        user = None
+    if user is not None and account_activation_token.check_token(user, token):
+        user.is_active = True
+        user.save()
+        login(request, user, backend='django.contrib.auth.backends.ModelBackend')
+        return redirect('projects')
+    else:
+        return render(request, 'validate_mail_address_invalid.html')