diff --git a/core/admin/mailu/ui/views/users.py b/core/admin/mailu/ui/views/users.py
index d3816c4a..6487c326 100644
--- a/core/admin/mailu/ui/views/users.py
+++ b/core/admin/mailu/ui/views/users.py
@@ -93,12 +93,12 @@ def user_settings(user_email):
     form = forms.UserSettingsForm(obj=user)
     utils.formatCSVField(form.forward_destination)
     if form.validate_on_submit():
-        if form.forward_enabled.data and (form.forward_destination.data in ['', None] or type(form.forward_destination.data) is list):
+        user.forward_enabled = bool(flask.request.form.get('forward_enabled', False))
+        if user.forward_enabled and not form.forward_destination.data:
             flask.flash('Destination email address is missing', 'error')
-            user.forward_enabled = True
-            return flask.render_template('user/settings.html', form=form, user=user)
-        if form.forward_enabled.data:
-            form.forward_destination.data = form.forward_destination.data.replace(" ","").split(",")
+            return flask.redirect(
+                flask.url_for('.user_settings', user_email=user_email))
+        form.forward_destination.data = form.forward_destination.data.replace(" ","").split(",")
         form.populate_obj(user)
         models.db.session.commit()
         form.forward_destination.data = ", ".join(form.forward_destination.data)
@@ -107,8 +107,9 @@ def user_settings(user_email):
             return flask.redirect(
                 flask.url_for('.user_list', domain_name=user.domain.name))
     elif form.is_submitted() and not form.validate():
-        user.forward_enabled = form.forward_enabled.data
-        return flask.render_template('user/settings.html', form=form, user=user)
+            flask.flash('Error validating the form', 'error')
+            return flask.redirect(
+                flask.url_for('.user_settings', user_email=user_email))
     return flask.render_template('user/settings.html', form=form, user=user)
 
 def _process_password_change(form, user_email):
diff --git a/core/admin/mailu/utils.py b/core/admin/mailu/utils.py
index 13522d79..2af352db 100644
--- a/core/admin/mailu/utils.py
+++ b/core/admin/mailu/utils.py
@@ -532,6 +532,7 @@ def isBadOrPwned(form):
 
 def formatCSVField(field):
     if not field.data:
+        field.data = ''
         return
     if isinstance(field.data,str):
         data = field.data.replace(" ","").split(",")
diff --git a/towncrier/newsfragments/3349.bugfix b/towncrier/newsfragments/3349.bugfix
new file mode 100644
index 00000000..b1dd1e0a
--- /dev/null
+++ b/towncrier/newsfragments/3349.bugfix
@@ -0,0 +1 @@
+Fix email-forwarding when set from the web interface