set from user id

app/mailers/application_mailer.rb

@@ -20,7 +20,7 @@ class ApplicationMailer < ActionMailer::Base
   end
 
   def set_message_metadata
-    message.instance_variable_set(:@message_metadata, @message_metadata)
+    message.instance_variable_set(:@message_metadata, @message_metadata || {})
   end
 
   def set_message_uuid
@@ -28,10 +28,14 @@ class ApplicationMailer < ActionMailer::Base
   end
 
   def assign_message_metadata(tag, record)
-    @message_metadata = {
+    @message_metadata = (@message_metadata || {}).merge(
       'tag' => tag,
       'record_id' => record.id,
       'record_type' => record.class.name
-    }
+    )
+  end
+
+  def put_metadata(attrs)
+    @message_metadata = (@message_metadata || {}).merge(attrs)
   end
 end

app/mailers/submitter_mailer.rb

@@ -233,9 +233,17 @@ class SubmitterMailer < ApplicationMailer
   def from_address_for_submitter(submitter)
     if submitter.submission.source.in?(%w[api embed]) &&
        (from_email = AccountConfig.find_by(account: submitter.account, key: 'integration_from_email')&.value.presence)
+      user = submitter.account.users.find_by(email: from_email)
+
+      put_metadata('from_user_id' => user.id)
+
       from_email
     else
-      (submitter.submission.created_by_user || submitter.submission.template.author).friendly_name
+      user = submitter.submission.created_by_user || submitter.submission.template.author
+
+      put_metadata('from_user_id' => user.id)
+
+      user.friendly_name
     end
   end
 end