feat: block free email provider signups

Mirrors the existing client-side check in the v3 signup form
(company-email-validator via Vuelidate) so non-business emails can no
longer slip in via Google OAuth, direct API calls, or any other path
that bypassed the form.

The deny list ships as config/deny_listed_email_domains.yml — picked up
automatically by ValidEmail2 — and is trimmed to the 6.5k consumer-only
domains the gem's disposable list doesn't already cover.

app/services/account/sign_up_email_validation_service.rb

@@ -17,6 +17,8 @@ class Account::SignUpEmailValidationService
 
     raise InvalidEmail.new({ valid: true, disposable: true }) if address.disposable?
 
+    raise InvalidEmail.new({ free_email_provider: true }) if address.deny_listed?
+
     true
   end
 

config/locales/en.yml

@@ -60,6 +60,7 @@ en:
     signup:
       disposable_email: We do not allow disposable emails
       blocked_domain: This domain is not allowed. If you believe this is a mistake, please contact support.
+      free_email_provider: Please sign up with your work email address.
       invalid_email: You have entered an invalid email
       email_already_exists: 'You have already signed up for an account with %{email}'
       invalid_params: 'Invalid, please check the signup paramters and try again'

lib/custom_exceptions/account.rb

@@ -7,6 +7,8 @@ module CustomExceptions::Account
         I18n.t 'errors.signup.blocked_domain'
       elsif @data[:disposable]
         I18n.t 'errors.signup.disposable_email'
+      elsif @data[:free_email_provider]
+        I18n.t 'errors.signup.free_email_provider'
       elsif !@data[:valid]
         I18n.t 'errors.signup.invalid_email'
       end

spec/services/account/sign_up_email_validation_service_spec.rb

@@ -5,7 +5,8 @@ require 'rails_helper'
 RSpec.describe Account::SignUpEmailValidationService, type: :service do
   let(:service) { described_class.new(email) }
   let(:blocked_domains) { "gmail.com\noutlook.com" }
-  let(:valid_email_address) { instance_double(ValidEmail2::Address, valid?: true, disposable?: false) }
+  let(:valid_email_address) { instance_double(ValidEmail2::Address, valid?: true, disposable?: false, deny_listed?: false) }
+  let(:free_provider_email_address) { instance_double(ValidEmail2::Address, valid?: true, disposable?: false, deny_listed?: true) }
   let(:disposable_email_address) { instance_double(ValidEmail2::Address, valid?: true, disposable?: true) }
   let(:invalid_email_address) { instance_double(ValidEmail2::Address, valid?: false) }
 
@@ -62,9 +63,21 @@ RSpec.describe Account::SignUpEmailValidationService, type: :service do
       end
     end
 
-    context 'when email is valid business email' do
+    context 'when email is from a free provider' do
       let(:email) { 'test@example.com' }
 
+      it 'raises InvalidEmail with free email provider message' do
+        allow(ValidEmail2::Address).to receive(:new).with(email).and_return(free_provider_email_address)
+        expect { service.perform }.to raise_error do |error|
+          expect(error.class.name).to eq('CustomExceptions::Account::InvalidEmail')
+          expect(error.message).to eq(I18n.t('errors.signup.free_email_provider'))
+        end
+      end
+    end
+
+    context 'when email is valid business email' do
+      let(:email) { 'test@chatwoot.com' }
+
       it 'returns true' do
         allow(ValidEmail2::Address).to receive(:new).with(email).and_return(valid_email_address)
         expect(service.perform).to be(true)