diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 99c836deb1..e8b203c9d6 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -845,7 +845,6 @@ Layout/SpaceInsideHashLiteralBraces:
     - 'spec/features/admin/reports_spec.rb'
     - 'spec/features/consumer/shopping/checkout_spec.rb'
     - 'spec/helpers/checkout_helper_spec.rb'
-    - 'spec/helpers/i18n_helper_spec.rb'
     - 'spec/helpers/order_cycles_helper_spec.rb'
     - 'spec/lib/open_food_network/enterprise_fee_calculator_spec.rb'
     - 'spec/lib/open_food_network/feature_toggle_spec.rb'
diff --git a/app/controllers/user_registrations_controller.rb b/app/controllers/user_registrations_controller.rb
index cc43badbb8..e8e75dc5ee 100644
--- a/app/controllers/user_registrations_controller.rb
+++ b/app/controllers/user_registrations_controller.rb
@@ -5,25 +5,29 @@ class UserRegistrationsController < Spree::UserRegistrationsController
 
   before_filter :set_checkout_redirect, only: :create
 
+  include I18nHelper
+  before_filter :set_locale
+
   # POST /resource/sign_up
   def create
     @user = build_resource(params[:spree_user])
-    if resource.save
-      session[:spree_user_signup] = true
-      session[:confirmation_return_url] = params[:return_url]
-      associate_user
+    @user.locale = I18n.locale.to_s
+    unless resource.save
+      return render_error(@user.errors)
+    end
 
-      respond_to do |format|
-        format.html do
-          set_flash_message(:success, :signed_up_but_unconfirmed)
-          redirect_to after_sign_in_path_for(@user)
-        end
-        format.js do
-          render json: { email: @user.email }
-        end
+    session[:spree_user_signup] = true
+    session[:confirmation_return_url] = params[:return_url]
+    associate_user
+
+    respond_to do |format|
+      format.html do
+        set_flash_message(:success, :signed_up_but_unconfirmed)
+        redirect_to after_sign_in_path_for(@user)
+      end
+      format.js do
+        render json: { email: @user.email }
       end
-    else
-      render_error(@user.errors)
     end
   rescue StandardError => error
     OpenFoodNetwork::ErrorLogger.notify(error)
diff --git a/app/helpers/i18n_helper.rb b/app/helpers/i18n_helper.rb
index 4c93bdc0bc..3293d42d98 100644
--- a/app/helpers/i18n_helper.rb
+++ b/app/helpers/i18n_helper.rb
@@ -1,7 +1,7 @@
 module I18nHelper
   def set_locale
     # Save a given locale
-    if params[:locale] && Rails.application.config.i18n.available_locales.include?(params[:locale])
+    if params[:locale] && available_locale?(params[:locale])
       spree_current_user.update_attributes!(locale: params[:locale]) if spree_current_user
       cookies[:locale] = params[:locale]
     end
@@ -13,4 +13,20 @@ module I18nHelper
 
     I18n.locale = spree_current_user.andand.locale || cookies[:locale] || I18n.default_locale
   end
+
+  def valid_locale(user)
+    if user.present? &&
+       user.locale.present? &&
+       available_locale?(user.locale)
+      user.locale
+    else
+      I18n.default_locale
+    end
+  end
+
+  private
+
+  def available_locale?(locale)
+    Rails.application.config.i18n.available_locales.include?(locale)
+  end
 end
diff --git a/app/mailers/enterprise_mailer.rb b/app/mailers/enterprise_mailer.rb
index 03d9279c93..36a1b071a9 100644
--- a/app/mailers/enterprise_mailer.rb
+++ b/app/mailers/enterprise_mailer.rb
@@ -1,15 +1,18 @@
 require 'devise/mailers/helpers'
 class EnterpriseMailer < Spree::BaseMailer
   include Devise::Mailers::Helpers
+  include I18nHelper
 
   def welcome(enterprise)
     @enterprise = enterprise
-    subject = t('enterprise_mailer.welcome.subject',
-                enterprise: @enterprise.name,
-                sitename: Spree::Config[:site_name])
-    mail(:to => enterprise.contact.email,
-         :from => from_address,
-         :subject => subject)
+    I18n.with_locale valid_locale(@enterprise.owner) do
+      subject = t('enterprise_mailer.welcome.subject',
+                  enterprise: @enterprise.name,
+                  sitename: Spree::Config[:site_name])
+      mail(:to => enterprise.contact.email,
+           :from => from_address,
+           :subject => subject)
+    end
   end
 
   def manager_invitation(enterprise, user)
@@ -17,11 +20,12 @@ class EnterpriseMailer < Spree::BaseMailer
     @instance = Spree::Config[:site_name]
     @instance_email = from_address
 
-    subject = t('enterprise_mailer.invite_manager.subject', enterprise: @enterprise.name)
-
-    mail(to: user.email,
-         from: from_address,
-         subject: subject)
+    I18n.with_locale valid_locale(@enterprise.owner) do
+      subject = t('enterprise_mailer.invite_manager.subject', enterprise: @enterprise.name)
+      mail(to: user.email,
+           from: from_address,
+           subject: subject)
+    end
   end
 
   private
diff --git a/app/mailers/producer_mailer.rb b/app/mailers/producer_mailer.rb
index ad7569dad2..058d5403ba 100644
--- a/app/mailers/producer_mailer.rb
+++ b/app/mailers/producer_mailer.rb
@@ -1,4 +1,5 @@
 class ProducerMailer < Spree::BaseMailer
+  include I18nHelper
 
   def order_cycle_report(producer, order_cycle)
     @producer = producer
@@ -10,9 +11,11 @@ class ProducerMailer < Spree::BaseMailer
     @total = total_from_line_items(line_items)
     @tax_total = tax_total_from_line_items(line_items)
 
-    subject = "[#{Spree::Config.site_name}] #{I18n.t('producer_mailer.order_cycle.subject', producer: producer.name)}"
+    I18n.with_locale valid_locale(@producer.owner) do
+      order_cycle_subject = I18n.t('producer_mailer.order_cycle.subject', producer: producer.name)
+      subject = "[#{Spree::Config.site_name}] #{order_cycle_subject}"
 
-    if has_orders?(order_cycle, producer)
+      return unless has_orders?(order_cycle, producer)
       mail(
         to: @producer.contact.email,
         from: from_address,
@@ -23,7 +26,6 @@ class ProducerMailer < Spree::BaseMailer
     end
   end
 
-
   private
 
   def has_orders?(order_cycle, producer)
diff --git a/app/mailers/spree/order_mailer_decorator.rb b/app/mailers/spree/order_mailer_decorator.rb
index a4b2db8b70..7d2cce4609 100644
--- a/app/mailers/spree/order_mailer_decorator.rb
+++ b/app/mailers/spree/order_mailer_decorator.rb
@@ -2,44 +2,59 @@ Spree::OrderMailer.class_eval do
   helper HtmlHelper
   helper CheckoutHelper
   helper SpreeCurrencyHelper
+  include I18nHelper
 
   def cancel_email(order, resend = false)
     @order = find_order(order)
-    subject = (resend ? "[#{t(:resend).upcase}] " : '')
-    subject += "#{Spree::Config[:site_name]} #{t('order_mailer.cancel_email.subject')} ##{order.number}"
-    mail(to: order.email, from: from_address, subject: subject)
+    I18n.with_locale valid_locale(@order.user) do
+      mail(to: order.email,
+           from: from_address,
+           subject: mail_subject(t('order_mailer.cancel_email.subject'), resend))
+    end
   end
 
   def confirm_email_for_customer(order, resend = false)
     find_order(order) # Finds an order instance from an id
-    subject = (resend ? "[#{t(:resend).upcase}] " : '')
-    subject += "#{Spree::Config[:site_name]} #{t('order_mailer.confirm_email.subject')} ##{@order.number}"
-    mail(:to => @order.email,
-         :from => from_address,
-         :subject => subject,
-         :reply_to => @order.distributor.contact.email)
+    I18n.with_locale valid_locale(@order.user) do
+      mail(to: @order.email,
+           from: from_address,
+           subject: mail_subject(t('order_mailer.confirm_email.subject'), resend),
+           reply_to: @order.distributor.contact.email)
+    end
   end
 
   def confirm_email_for_shop(order, resend = false)
     find_order(order) # Finds an order instance from an id
-    subject = (resend ? "[#{t(:resend).upcase}] " : '')
-    subject += "#{Spree::Config[:site_name]} #{t('order_mailer.confirm_email.subject')} ##{@order.number}"
-    mail(:to => @order.distributor.contact.email,
-         :from => from_address,
-         :subject => subject)
+    I18n.with_locale valid_locale(@order.user) do
+      mail(to: @order.distributor.contact.email,
+           from: from_address,
+           subject: mail_subject(t('order_mailer.confirm_email.subject'), resend))
+    end
   end
 
   def invoice_email(order, pdf)
     find_order(order) # Finds an order instance from an id
-    attachments["invoice-#{@order.number}.pdf"] = pdf if pdf.present?
-    subject = "#{Spree::Config[:site_name]} #{t(:invoice)} ##{@order.number}"
-    mail(:to => @order.email,
-         :from => from_address,
-         :subject => subject,
-         :reply_to => @order.distributor.contact.email)
+    attach_file("invoice-#{@order.number}.pdf", pdf)
+    I18n.with_locale valid_locale(@order.user) do
+      mail(to: @order.email,
+           from: from_address,
+           subject: mail_subject(t(:invoice), false),
+           reply_to: @order.distributor.contact.email)
+    end
   end
 
   def find_order(order)
     @order = order.respond_to?(:id) ? order : Spree::Order.find(order)
   end
+
+  private
+
+  def mail_subject(base_subject, resend)
+    resend_prefix = (resend ? "[#{t(:resend).upcase}] " : '')
+    "#{resend_prefix}#{Spree::Config[:site_name]} #{base_subject} ##{@order.number}"
+  end
+
+  def attach_file(filename, file)
+    attachments[filename] = file if file.present?
+  end
 end
diff --git a/app/mailers/spree/user_mailer_decorator.rb b/app/mailers/spree/user_mailer_decorator.rb
index dced31e7fd..f9e618e348 100644
--- a/app/mailers/spree/user_mailer_decorator.rb
+++ b/app/mailers/spree/user_mailer_decorator.rb
@@ -1,8 +1,12 @@
 Spree::UserMailer.class_eval do
+  include I18nHelper
+
   def signup_confirmation(user)
     @user = user
-    mail(:to => user.email, :from => from_address,
-         :subject => t(:welcome_to) + Spree::Config[:site_name])
+    I18n.with_locale valid_locale(@user) do
+      mail(:to => user.email, :from => from_address,
+           :subject => t(:welcome_to) + Spree::Config[:site_name])
+    end
   end
 
   # Overriding `Spree::UserMailer.confirmation_instructions` which is
@@ -12,10 +16,12 @@ Spree::UserMailer.class_eval do
     @instance = Spree::Config[:site_name]
     @contact = ContentConfig.footer_email
 
-    subject = t('spree.user_mailer.confirmation_instructions.subject')
-    mail(to: confirmation_email_address,
-         from: from_address,
-         subject: subject)
+    I18n.with_locale valid_locale(@user) do
+      subject = t('spree.user_mailer.confirmation_instructions.subject')
+      mail(to: confirmation_email_address,
+           from: from_address,
+           subject: subject)
+    end
   end
 
   private
diff --git a/app/mailers/subscription_mailer.rb b/app/mailers/subscription_mailer.rb
index 426d94f847..0046155499 100644
--- a/app/mailers/subscription_mailer.rb
+++ b/app/mailers/subscription_mailer.rb
@@ -1,6 +1,7 @@
 class SubscriptionMailer < Spree::BaseMailer
   helper CheckoutHelper
   helper ShopMailHelper
+  include I18nHelper
 
   def confirmation_email(order)
     @type = 'confirmation'
@@ -46,10 +47,13 @@ class SubscriptionMailer < Spree::BaseMailer
   private
 
   def send_mail(order)
-    subject = "#{Spree::Config[:site_name]} #{t('order_mailer.confirm_email.subject')} ##{order.number}"
-    mail(to: order.email,
-         from: from_address,
-         subject: subject,
-         reply_to: order.distributor.contact.email)
+    I18n.with_locale valid_locale(order.user) do
+      confirm_email_subject = t('order_mailer.confirm_email.subject')
+      subject = "#{Spree::Config[:site_name]} #{confirm_email_subject} ##{order.number}"
+      mail(to: order.email,
+           from: from_address,
+           subject: subject,
+           reply_to: order.distributor.contact.email)
+    end
   end
 end
diff --git a/spec/controllers/user_registrations_controller_spec.rb b/spec/controllers/user_registrations_controller_spec.rb
index 7ed7951c50..22d14b383f 100644
--- a/spec/controllers/user_registrations_controller_spec.rb
+++ b/spec/controllers/user_registrations_controller_spec.rb
@@ -48,6 +48,16 @@ describe UserRegistrationsController, type: :controller do
       expect(json).to eq({"email" => "test@test.com"})
       expect(controller.spree_current_user).to be_nil
     end
+
+    it "sets user.locale from cookie on create" do
+      original_locale_cookie = cookies[:locale]
+      cookies[:locale] = "pt"
+
+      xhr :post, :create, spree_user: user_params, use_route: :spree
+
+      expect(assigns[:user].locale).to eq("pt")
+      cookies[:locale] = original_locale_cookie
+    end
   end
 
   context "when registration fails" do
diff --git a/spec/helpers/i18n_helper_spec.rb b/spec/helpers/i18n_helper_spec.rb
index 62c58e2345..fba8ab882b 100644
--- a/spec/helpers/i18n_helper_spec.rb
+++ b/spec/helpers/i18n_helper_spec.rb
@@ -24,13 +24,13 @@ describe I18nHelper, type: :helper do
     end
 
     it "sets the chosen locale" do
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
       expect(I18n.locale).to eq :es
     end
 
     it "remembers the chosen locale" do
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
 
       allow(helper).to receive(:params) { {} }
@@ -39,16 +39,16 @@ describe I18nHelper, type: :helper do
     end
 
     it "ignores unavailable locales" do
-      allow(helper).to receive(:params) { {locale: "xx"} }
+      allow(helper).to receive(:params) { { locale: "xx" } }
       helper.set_locale
       expect(I18n.locale).to eq :en
     end
 
     it "remembers the last chosen locale" do
-      allow(helper).to receive(:params) { {locale: "en"} }
+      allow(helper).to receive(:params) { { locale: "en" } }
       helper.set_locale
 
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
 
       allow(helper).to receive(:params) { {} }
@@ -57,7 +57,7 @@ describe I18nHelper, type: :helper do
     end
 
     it "remembers the chosen locale after logging in" do
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
 
       # log in
@@ -68,7 +68,7 @@ describe I18nHelper, type: :helper do
     end
 
     it "forgets the chosen locale without cookies" do
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
 
       # clean up cookies
@@ -91,14 +91,14 @@ describe I18nHelper, type: :helper do
     end
 
     it "sets the chosen locale" do
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
       expect(I18n.locale).to eq :es
       expect(user.locale).to eq "es"
     end
 
     it "remembers the chosen locale" do
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
 
       allow(helper).to receive(:params) { {} }
@@ -107,10 +107,10 @@ describe I18nHelper, type: :helper do
     end
 
     it "remembers the last chosen locale" do
-      allow(helper).to receive(:params) { {locale: "en"} }
+      allow(helper).to receive(:params) { { locale: "en" } }
       helper.set_locale
 
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
 
       allow(helper).to receive(:params) { {} }
@@ -119,7 +119,7 @@ describe I18nHelper, type: :helper do
     end
 
     it "remembers the chosen locale after logging out" do
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
 
       # log out
@@ -130,7 +130,7 @@ describe I18nHelper, type: :helper do
     end
 
     it "remembers the chosen locale on another computer" do
-      allow(helper).to receive(:params) { {locale: "es"} }
+      allow(helper).to receive(:params) { { locale: "es" } }
       helper.set_locale
       expect(cookies[:locale]).to eq "es"
 
@@ -142,4 +142,36 @@ describe I18nHelper, type: :helper do
       expect(I18n.locale).to eq :es
     end
   end
+
+  context "#valid_locale" do
+    around do |example|
+      original_default_locale = I18n.default_locale
+      original_available_locales = Rails.application.config.i18n.available_locales
+      I18n.default_locale = "es"
+      Rails.application.config.i18n.available_locales = ["es", "pt"]
+      example.run
+      I18n.default_locale = original_default_locale
+      Rails.application.config.i18n.available_locales = original_available_locales
+    end
+
+    let(:user) { build(:user) }
+
+    it "returns default locale if given user is nil" do
+      expect(helper.valid_locale(nil)).to eq I18n.default_locale
+    end
+
+    it "returns default locale if locale of given user is nil" do
+      expect(helper.valid_locale(user)).to eq I18n.default_locale
+    end
+
+    it "returns default locale if locale of given user is not available" do
+      user.locale = "cn"
+      expect(helper.valid_locale(user)).to eq I18n.default_locale
+    end
+
+    it "returns the locale of the given user if available" do
+      user.locale = "pt"
+      expect(helper.valid_locale(user)).to eq "pt"
+    end
+  end
 end
diff --git a/spec/mailers/user_mailer_spec.rb b/spec/mailers/user_mailer_spec.rb
index 8082d0f6a6..9b4790e5ad 100644
--- a/spec/mailers/user_mailer_spec.rb
+++ b/spec/mailers/user_mailer_spec.rb
@@ -17,9 +17,32 @@ describe Spree::UserMailer do
     setup_email
   end
 
-  it "sends an email when given a user" do
-    Spree::UserMailer.signup_confirmation(user).deliver
-    ActionMailer::Base.deliveries.count.should == 1
+  describe '#signup_confirmation' do
+    it "sends email when given a user" do
+      Spree::UserMailer.signup_confirmation(user).deliver
+      expect(ActionMailer::Base.deliveries.count).to eq(1)
+    end
+
+    describe "user locale" do
+      around do |example|
+        original_default_locale = I18n.default_locale
+        I18n.default_locale = 'pt'
+        example.run
+        I18n.default_locale = original_default_locale
+      end
+
+      it "sends email in user locale when user locale is defined" do
+        user.locale = 'es'
+        Spree::UserMailer.signup_confirmation(user).deliver
+        expect(ActionMailer::Base.deliveries.first.body).to include "Gracias por unirte"
+      end
+
+      it "sends email in default locale when user locale is not available" do
+        user.locale = 'cn'
+        Spree::UserMailer.signup_confirmation(user).deliver
+        expect(ActionMailer::Base.deliveries.first.body).to include "Obrigada por juntar-se"
+      end
+    end
   end
 
   # adapted from https://github.com/spree/spree_auth_devise/blob/70737af/spec/mailers/user_mailer_spec.rb