diff --git a/app/services/integrations/slack/incoming_message_builder.rb b/app/services/integrations/slack/incoming_message_builder.rb
index 6d0cccad0..23d633b1d 100644
--- a/app/services/integrations/slack/incoming_message_builder.rb
+++ b/app/services/integrations/slack/incoming_message_builder.rb
@@ -36,7 +36,7 @@ class Integrations::Slack::IncomingMessageBuilder
   def should_process_event?
     return true if params[:type] != 'event_callback'
 
-    params[:event][:user].present? && params[:event][:subtype].blank?
+    params[:event][:user].present? && valid_event_subtype?
   end
 
   def valid_event_subtype?
@@ -97,7 +97,14 @@ class Integrations::Slack::IncomingMessageBuilder
   def create_message
     return unless conversation
 
-    @message = conversation.messages.create!(
+    build_message
+    process_attachments(params[:event][:files]) if params[:event][:files].present?
+    @message.save!
+    { status: 'success' }
+  end
+
+  def build_message
+    @message = conversation.messages.build(
       message_type: :outgoing,
       account_id: conversation.account_id,
       inbox_id: conversation.inbox_id,
@@ -106,10 +113,6 @@ class Integrations::Slack::IncomingMessageBuilder
       private: private_note?,
       sender: sender
     )
-
-    process_attachments(params[:event][:files]) if params[:event][:files].present?
-
-    { status: 'success' }
   end
 
   def slack_client
@@ -135,7 +138,6 @@ class Integrations::Slack::IncomingMessageBuilder
 
       attachment_obj = @message.attachments.new(attachment_params)
       attachment_obj.file.content_type = attachment[:mimetype]
-      attachment_obj.save!
     end
   end
 
diff --git a/config/integration/apps.yml b/config/integration/apps.yml
index 05add0c1a..b71df9813 100644
--- a/config/integration/apps.yml
+++ b/config/integration/apps.yml
@@ -13,7 +13,7 @@ slack:
   id: slack
   logo: slack.png
   i18n_key: slack
-  action: https://slack.com/oauth/v2/authorize?scope=commands,chat:write,channels:read,channels:manage,channels:join,groups:read,groups:write,im:write,mpim:write,users:read,users:read.email,chat:write.customize,channels:history,groups:history,mpim:history,im:history
+  action: https://slack.com/oauth/v2/authorize?scope=commands,chat:write,channels:read,channels:manage,channels:join,groups:read,groups:write,im:write,mpim:write,users:read,users:read.email,chat:write.customize,channels:history,groups:history,mpim:history,im:history,files:read
   hook_type: account
   allow_multiple_hooks: false
 webhooks: