diff --git a/config/initializers/feature_toggles.rb b/config/initializers/feature_toggles.rb
index 13d083979c..9c31940462 100644
--- a/config/initializers/feature_toggles.rb
+++ b/config/initializers/feature_toggles.rb
@@ -1,5 +1,11 @@
 require 'open_food_network/feature_toggle'
 
-beta_testers = ENV['BETA_TESTERS']&.split(/[\s,]+/)
+beta_testers = ENV['BETA_TESTERS']&.split(/[\s,]+/) || []
 
-OpenFoodNetwork::FeatureToggle.enable(:customer_balance, beta_testers)
+OpenFoodNetwork::FeatureToggle.enable(:customer_balance) do |user|
+  if beta_testers == ['all']
+    true
+  else
+    beta_testers.include?(user.email)
+  end
+end
diff --git a/lib/open_food_network/feature_toggle.rb b/lib/open_food_network/feature_toggle.rb
index 5ee51a82f9..f57e740bc4 100644
--- a/lib/open_food_network/feature_toggle.rb
+++ b/lib/open_food_network/feature_toggle.rb
@@ -30,11 +30,9 @@ module OpenFoodNetwork
       new.enabled?(feature_name, user)
     end
 
-    def self.enable(feature_name, user_emails)
-      return unless user_emails.present?
-
+    def self.enable(feature_name, &block)
       Thread.current[:features] ||= {}
-      Thread.current[:features][feature_name] = Feature.new(user_emails)
+      Thread.current[:features][feature_name] = Feature.new(block)
     end
 
     def initialize
@@ -68,17 +66,17 @@ module OpenFoodNetwork
   end
 
   class Feature
-    def initialize(users = [])
-      @users = users
+    def initialize(block)
+      @block = block
     end
 
     def enabled?(user)
-      users.include?(user.email)
+      block.call(user)
     end
 
     private
 
-    attr_reader :users
+    attr_reader :block
   end
 
   class NullFeature
diff --git a/spec/initializers/feature_toggles_spec.rb b/spec/initializers/feature_toggles_spec.rb
new file mode 100644
index 0000000000..0433d4508b
--- /dev/null
+++ b/spec/initializers/feature_toggles_spec.rb
@@ -0,0 +1,65 @@
+require 'spec_helper'
+
+describe 'config/initializers/feature_toggles.rb' do
+  # Executes the initializer's code block by reading the Ruby file. Note that `Kernel#require` would
+  # prevent this from happening twice.
+  subject(:execute_initializer) do
+    load Rails.root.join('config/initializers/feature_toggles.rb')
+  end
+
+  let(:user) { build(:user) }
+
+  around do |example|
+    original = ENV['BETA_TESTERS']
+    example.run
+    ENV['BETA_TESTERS'] = original
+  end
+
+  context 'when beta_testers is ["all"]' do
+    before { ENV['BETA_TESTERS'] = 'all' }
+
+    it 'returns true' do
+      execute_initializer
+
+      enabled = OpenFoodNetwork::FeatureToggle.enabled?(:customer_balance, user)
+      expect(enabled).to eq(true)
+    end
+  end
+
+  context 'when beta_testers is a list of emails' do
+    let(:other_user) { build(:user) }
+
+    context 'and the user is in the list' do
+      before { ENV['BETA_TESTERS'] = "#{user.email}, #{other_user.email}" }
+
+      it 'enables the feature' do
+        execute_initializer
+
+        enabled = OpenFoodNetwork::FeatureToggle.enabled?(:customer_balance, user)
+        expect(enabled).to eq(true)
+      end
+    end
+
+    context 'and the user is not in the list' do
+      before { ENV['BETA_TESTERS'] = "#{other_user.email}" }
+
+      it 'disables the feature' do
+        execute_initializer
+
+        enabled = OpenFoodNetwork::FeatureToggle.enabled?(:customer_balance, user)
+        expect(enabled).to eq(false)
+      end
+    end
+
+    context 'and the list is empty' do
+      before { ENV['BETA_TESTERS'] = '' }
+
+      it 'disables the feature' do
+        execute_initializer
+
+        enabled = OpenFoodNetwork::FeatureToggle.enabled?(:customer_balance, user)
+        expect(enabled).to eq(false)
+      end
+    end
+  end
+end
diff --git a/spec/lib/open_food_network/feature_toggle_spec.rb b/spec/lib/open_food_network/feature_toggle_spec.rb
index 73407d671d..d9904b0fd6 100644
--- a/spec/lib/open_food_network/feature_toggle_spec.rb
+++ b/spec/lib/open_food_network/feature_toggle_spec.rb
@@ -32,19 +32,25 @@ module OpenFoodNetwork
     context 'when specifying users' do
       let(:user) { build(:user) }
 
-      context 'and the feature is enabled for them' do
-        before { FeatureToggle.enable(:foo, [user.email]) }
+      context 'and the block does not specify arguments' do
+        before do
+          FeatureToggle.enable(:foo) { 'return value' }
+        end
 
-        it 'returns true' do
-          expect(FeatureToggle.enabled?(:foo, user)).to eq(true)
+        it "returns the block's return value" do
+          expect(FeatureToggle.enabled?(:foo, user)).to eq('return value')
         end
       end
 
-      context 'and the feature is disabled for them' do
-        before { FeatureToggle.enable(:foo, []) }
+      context 'and the block specifies arguments' do
+        let(:users) { [user.email] }
 
-        it 'returns false' do
-          expect(FeatureToggle.enabled?(:foo, user)).to eq(false)
+        before do
+          FeatureToggle.enable(:foo) { |user| users.include?(user.email) }
+        end
+
+        it "returns the block's return value" do
+          expect(FeatureToggle.enabled?(:foo, user)).to eq(true)
         end
       end
     end