reset SMTP transaction automatically after any DATA response, not just success

lib/postal/smtp_server/client.rb

@@ -378,10 +378,14 @@ module Postal
 
       def finished
         if @data.bytesize > Postal.config.smtp_server.max_message_size.megabytes.to_i
+          transaction_reset
+          @state = :welcomed
           return "552 Message too large (maximum size %dMB)" % Postal.config.smtp_server.max_message_size
         end
 
         if @headers['received'].select { |r| r =~ /by #{Postal.config.dns.smtp_server_hostname}/ }.count > 4
+          transaction_reset
+          @state = :welcomed
           return '550 Loop detected'
         end
 
@@ -389,6 +393,8 @@ module Postal
         if @credential
           authenticated_domain = @credential.server.find_authenticated_domain_from_headers(@headers)
           if authenticated_domain.nil?
+            transaction_reset
+            @state = :welcomed
             return '530 From/Sender name is not valid'
           end
         end