diff --git a/Gemfile b/Gemfile
index 017dbd5..0fec91c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -35,7 +35,7 @@ gem 'lingua_franca', git: 'https://github.com/lingua-franca/lingua_franca.git',
 gem 'marmara', git: 'https://github.com/lingua-franca/marmara.git', branch: 'master'
 
 # Bike!Bike! specific stuff
-gem 'paypal-express', git: 'https://github.com/ianfleeton/paypal-express'
+gem 'ianfleeton-paypal-express', require: 'paypal/express'
 gem 'geocoder'
 gem 'sitemap_generator'
 gem 'sass-json-vars'
@@ -83,7 +83,10 @@ group :production, :preview do
 end
 
 group :production, :preview do
-  gem 'unicorn', require: false
+  platforms :ruby do
+    gem 'unicorn', require: false
+  end
+
   gem 'daemon-spawn'
   gem 'daemons'
 end
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 0831da0..58c5c92 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -103,18 +103,28 @@ class ApplicationController < BaseController
       # log the error
       logger.info "A JavaScript error has occurred on #{params[:location]}:#{params[:lineNumber]}: #{params[:message]}"
 
-      UserMailer.send_mail(:error_report) do 
-        [
-          "A JavaScript error has occurred",
-          report,
-          params[:message],
-          nil,
-          request,
-          params,
-          current_user,
-          Time.now.strftime("%d/%m/%Y %H:%M")
-        ]
-      end if Rails.env.preview? || Rails.env.production?
+      if Rails.env.preview? || Rails.env.production?
+        requestHash = {
+          'remote_ip'    => arg.remote_ip,
+          'uuid'         => arg.uuid,
+          'original_url' => arg.original_url,
+          'env'          => Hash.new
+        }
+        request.env.each do | key, value |
+          requestHash['env'][key.to_s] = value.to_s
+        end
+
+        UserMailer.error_report(
+            "A JavaScript error has occurred",
+            report,
+            params[:message],
+            nil,
+            requestHash,
+            params,
+            current_user,
+            Time.now.strftime("%d/%m/%Y %H:%M")
+        ).deliver_later!
+      end
     rescue Exception => exception2
       logger.info exception2.to_s
       logger.info exception2.backtrace.join("\n")
@@ -168,19 +178,28 @@ class ApplicationController < BaseController
     logger.info exception.backtrace.join("\n")
 
     # send and email if this is production
-    suppress(Exception) do
-      UserMailer.send_mail(:error_report) do 
-        [
-          "An error has occurred in #{Rails.env}",
-          nil,
-          exception.to_s,
-          exception.backtrace.join("\n"),
-          request,
-          params,
-          current_user,
-          Time.now.strftime("%d/%m/%Y %H:%M")
-        ]
-      end if Rails.env.preview? || Rails.env.production?
+    if Rails.env.preview? || Rails.env.production?
+      suppress(Exception) do
+        requestHash = {
+          'remote_ip'    => arg.remote_ip,
+          'uuid'         => arg.uuid,
+          'original_url' => arg.original_url,
+          'env'          => Hash.new
+        }
+        request.env.each do | key, value |
+          requestHash['env'][key.to_s] = value.to_s
+        end
+        UserMailer.error_report(
+            "An error has occurred in #{Rails.env}",
+            nil,
+            exception.to_s,
+            exception.backtrace.join("\n"),
+            requestHash,
+            params,
+            current_user,
+            Time.now.strftime("%d/%m/%Y %H:%M")
+        ).deliver_later!
+      end
     end
 
     # raise the error if we are in development so that we can debug it
@@ -211,25 +230,21 @@ class ApplicationController < BaseController
       end
     end
 
-    UserMailer.send_mail(:contact) do 
-      [
+    UserMailer.contact(
         current_user || params[:email],
         params[:subject],
         params[:message],
         email_list
-      ]
-    end
+      ).deliver_later
 
     request_info = session['request_info'] || { 'request' => request, 'params' => params }
-    UserMailer.send_mail(:contact_details) do 
-      [
+    UserMailer.contact_details(
         current_user || params[:email],
         params[:subject],
         params[:message],
         request_info['request'],
         request_info['params']
-      ]
-    end
+      ).deliver_later
 
     redirect_to contact_sent_path
   end
@@ -303,8 +318,8 @@ class ApplicationController < BaseController
     if object.respond_to?(:get_translators)
       object.get_translators(data, locale).each do |id, user|
         if user.id != current_user.id && user.id != translator_id
-          UserMailer.send_mail mailer, user.locale do
-            { :args => [object, data, locale, user, translator] }
+          LinguaFranca.with_locale user.locale do
+            UserMailer.send(mailer, object.id, data, locale, user.id, translator.id).deliver_later
           end
         end
       end
@@ -317,8 +332,8 @@ class ApplicationController < BaseController
     if object.respond_to?(:get_translators)
       object.get_translators(data).each do |id, user|
         if user.id != current_user.id
-          UserMailer.send_mail mailer, user.locale do
-            { :args => [object, data, user, current_user] }
+          LinguaFranca.with_locale user.locale do
+            UserMailer.send(mailer, object.id, data, user.id, current_user.id)
           end
         end
       end
@@ -329,23 +344,32 @@ class ApplicationController < BaseController
     # log it
     logger.info "Missing translation found for: #{key}"
 
-    # send and email if this is production
-    begin
-      UserMailer.send_mail(:error_report) do 
-        [
-          "A missing translation found in #{Rails.env}",
-          "<p>A translation for <code>#{key}</code> in <code>#{locale.to_s}</code> was found. The text that was rendered to the user was:</p><blockquote>#{str || 'nil'}</blockquote>",
-          exception.to_s,
-          nil,
-          request,
-          params,
-          current_user,
-          Time.now.strftime("%d/%m/%Y %H:%M")
-        ]
-      end if Rails.env.preview? || Rails.env.production?
-    rescue Exception => exception2
-      logger.info exception2.to_s
-      logger.info exception2.backtrace.join("\n")
+    # send an email if this is production
+    if Rails.env.preview? || Rails.env.production?
+      begin
+        requestHash = {
+          'remote_ip'    => arg.remote_ip,
+          'uuid'         => arg.uuid,
+          'original_url' => arg.original_url,
+          'env'          => Hash.new
+        }
+        request.env.each do | key, value |
+          requestHash['env'][key.to_s] = value.to_s
+        end
+        UserMailer.error_report(
+            "A missing translation found in #{Rails.env}",
+            "<p>A translation for <code>#{key}</code> in <code>#{locale.to_s}</code> was found. The text that was rendered to the user was:</p><blockquote>#{str || 'nil'}</blockquote>",
+            exception.to_s,
+            nil,
+            requestHash,
+            params,
+            current_user.id,
+            Time.now.strftime("%d/%m/%Y %H:%M")
+        ).deliver_later!
+      rescue Exception => exception2
+        logger.info exception2.to_s
+        logger.info exception2.backtrace.join("\n")
+      end
     end
   end
 
@@ -608,6 +632,6 @@ class ApplicationController < BaseController
 
     # send the confirmation email and make sure it get sent as quickly as possible
     def send_confirmation(confirmation)
-      UserMailer.send_mail(:email_confirmation) { confirmation }
+      UserMailer.email_confirmation(confirmation.id).deliver_now
     end
 end
diff --git a/app/controllers/conference_administration_controller.rb b/app/controllers/conference_administration_controller.rb
index 2fef5c8..13b53d6 100644
--- a/app/controllers/conference_administration_controller.rb
+++ b/app/controllers/conference_administration_controller.rb
@@ -1015,16 +1015,13 @@ class ConferenceAdministrationController < ApplicationController
       @register_template = :administration
       if params[:button] == 'send'
         view_context.broadcast_to(@send_to).each do |user|
-          UserMailer.send_mail :broadcast do
-            [
+          UserMailer.broadcast(
               "#{request.protocol}#{request.host_with_port}",
               @subject,
               @body,
-              user,
-              @this_conference
-            ]
-          end
-        end
+              user.id,
+              @this_conference.id
+            ).deliver_later
         redirect_to administration_step_path(@this_conference.slug, :broadcast_sent)
         return true
       elsif params[:button] == 'preview'
@@ -1032,15 +1029,13 @@ class ConferenceAdministrationController < ApplicationController
         @broadcast_step = :preview
       elsif params[:button] == 'test'
         @broadcast_step = :test
-        UserMailer.send_mail :broadcast do
-          [
+        UserMailer.broadcast(
             "#{request.protocol}#{request.host_with_port}",
             @subject,
             @body,
-            current_user,
-            @this_conference
-          ]
-        end
+            current_user.id,
+            @this_conference.id
+          ).deliver_later
         @send_to_count = view_context.broadcast_to(@send_to).size
       end
       return false
diff --git a/app/controllers/workshops_controller.rb b/app/controllers/workshops_controller.rb
index ea7a64b..e835e70 100644
--- a/app/controllers/workshops_controller.rb
+++ b/app/controllers/workshops_controller.rb
@@ -217,11 +217,7 @@ class WorkshopsController < ApplicationController
     # create the request by making the user a facilitator but making their role 'requested'
     WorkshopFacilitator.create(user_id: current_user.id, workshop_id: workshop.id, role: :requested)
 
-    UserMailer.send_mail :workshop_facilitator_request do
-      {
-        :args => [ workshop, current_user, params[:message] ]
-      }
-    end
+    UserMailer.workshop_facilitator_request(workshop.id, current_user.id, params[:message]).deliver_later
 
     redirect_to sent_facilitate_workshop_url(@this_conference.slug, workshop.id)
   end
@@ -254,18 +250,18 @@ class WorkshopsController < ApplicationController
             workshop.id, user_id)
         f.role = :collaborator
         f.save
-        UserMailer.send_mail :workshop_facilitator_request_approved, user.locale do
-          [ workshop, user ]
+        LinguaFranca.with_locale(user.locale) do
+          UserMailer.workshop_facilitator_request_approved(workshop.id, user.id).deliver_later
         end
-        return redirect_to view_workshop_url(@this_conference.slug, workshop.id)    
+        return redirect_to view_workshop_url(@this_conference.slug, workshop.id)
       end
     when :deny
       if workshop.active_facilitator?(current_user) && workshop.requested_collaborator?(User.find(user_id))
         WorkshopFacilitator.delete_all(
           :workshop_id => workshop.id,
           :user_id => user_id)
-        UserMailer.send_mail :workshop_facilitator_request_denied, user.locale do
-          [ workshop, user ]
+        LinguaFranca.with_locale user.locale do
+          UserMailer.workshop_facilitator_request_denied(workshop.id, user.id).deliver_later
         end
         return redirect_to view_workshop_url(@this_conference.slug, workshop.id)    
       end
@@ -312,8 +308,8 @@ class WorkshopsController < ApplicationController
     unless workshop.facilitator?(user)
       WorkshopFacilitator.create(user_id: user.id, workshop_id: workshop.id, role: :collaborator)
       
-      UserMailer.send_mail :workshop_facilitator_request_approved, user.locale do
-        [ workshop, user ]
+      LinguaFranca.with_locale user.locale do
+        UserMailer.workshop_facilitator_request_approved(workshop.id, user.id).deliver_later
       end
     end
 
@@ -332,8 +328,8 @@ class WorkshopsController < ApplicationController
       new_comment = comment.add_comment(current_user, params[:reply])
 
       unless comment.user.id == current_user.id
-        UserMailer.send_mail :workshop_comment, comment.user.locale do
-          [ workshop, new_comment, comment.user ]
+        LinguaFranca.with_locale comment.user.locale do
+          UserMailer.workshop_comment(workshop.id, new_comment.id, comment.user.id).deliver_later
         end
       end
     elsif params[:button] = 'add_comment'
@@ -341,8 +337,8 @@ class WorkshopsController < ApplicationController
 
       workshop.active_facilitators.each do | u |
         unless u.id == current_user.id
-          UserMailer.send_mail :workshop_comment, u.locale do
-            [ workshop, new_comment, u ]
+          LinguaFranca.with_locale u.locale do
+            UserMailer.workshop_comment(workshop.id, new_comment.id, u.id).deliver_later
           end
         end
       end
diff --git a/features/support/location_cache.yml b/features/support/location_cache.yml
index 02508d1..9badcd9 100644
--- a/features/support/location_cache.yml
+++ b/features/support/location_cache.yml
@@ -251,6 +251,54 @@ Portland OR: !ruby/object:Geocoder::Result::Google
     - locality
     - political
   cache_hit: 
+Prince Rupert BC: !ruby/object:Geocoder::Result::Google
+  data:
+    address_components:
+    - long_name: Prince Rupert
+      short_name: Prince Rupert
+      types:
+      - locality
+      - political
+    - long_name: Skeena-Queen Charlotte
+      short_name: Skeena-Queen Charlotte
+      types:
+      - administrative_area_level_2
+      - political
+    - long_name: British Columbia
+      short_name: BC
+      types:
+      - administrative_area_level_1
+      - political
+    - long_name: Canada
+      short_name: CA
+      types:
+      - country
+      - political
+    formatted_address: Prince Rupert, BC, Canada
+    geometry:
+      bounds:
+        northeast:
+          lat: 54.338083
+          lng: -130.2437961
+        southwest:
+          lat: 54.19392
+          lng: -130.3634291
+      location:
+        lat: 54.3150367
+        lng: -130.3208187
+      location_type: APPROXIMATE
+      viewport:
+        northeast:
+          lat: 54.3343706
+          lng: -130.2478032
+        southwest:
+          lat: 54.202669
+          lng: -130.3608029
+    place_id: ChIJaUV_axPVclQRElbZTQ_jB3E
+    types:
+    - locality
+    - political
+  cache_hit: 
 Regina, SK: !ruby/object:Geocoder::Result::Google
   data:
     address_components:
@@ -453,51 +501,3 @@ Eldorado, MX: !ruby/object:Geocoder::Result::Google
     - locality
     - political
   cache_hit: 
-Prince Rupert BC: !ruby/object:Geocoder::Result::Google
-  data:
-    address_components:
-    - long_name: Prince Rupert
-      short_name: Prince Rupert
-      types:
-      - locality
-      - political
-    - long_name: Skeena-Queen Charlotte
-      short_name: Skeena-Queen Charlotte
-      types:
-      - administrative_area_level_2
-      - political
-    - long_name: British Columbia
-      short_name: BC
-      types:
-      - administrative_area_level_1
-      - political
-    - long_name: Canada
-      short_name: CA
-      types:
-      - country
-      - political
-    formatted_address: Prince Rupert, BC, Canada
-    geometry:
-      bounds:
-        northeast:
-          lat: 54.338083
-          lng: -130.2437961
-        southwest:
-          lat: 54.19392
-          lng: -130.3634291
-      location:
-        lat: 54.3150367
-        lng: -130.3208187
-      location_type: APPROXIMATE
-      viewport:
-        northeast:
-          lat: 54.3343706
-          lng: -130.2478032
-        southwest:
-          lat: 54.202669
-          lng: -130.3608029
-    place_id: ChIJaUV_axPVclQRElbZTQ_jB3E
-    types:
-    - locality
-    - political
-  cache_hit: