fix(message-dequeuer): ensure SMTP endpoints are sent to SMTP sender appropriately

closes #2853

app/lib/message_dequeuer/incoming_message_processor.rb

@@ -163,7 +163,7 @@ module MessageDequeuer
 
       case queued_message.message.endpoint
       when SMTPEndpoint
-        sender = @state.sender_for(SMTPSender, queued_message.message.recipient_domain, nil, servers: [queued_message.message.endpoint])
+        sender = @state.sender_for(SMTPSender, queued_message.message.recipient_domain, nil, servers: [queued_message.message.endpoint.to_smtp_client_server])
       when HTTPEndpoint
         sender = @state.sender_for(HTTPSender, queued_message.message.endpoint)
       when AddressEndpoint

app/models/smtp_endpoint.rb

@@ -47,4 +47,8 @@ class SMTPEndpoint < ApplicationRecord
     routes.each { |r| r.update(endpoint: nil, mode: "Reject") }
   end
 
+  def to_smtp_client_server
+    SMTPClient::Server.new(hostname, port: port || 25, ssl_mode: ssl_mode)
+  end
+
 end

spec/lib/message_dequeuer/incoming_message_processor_spec.rb

@@ -422,7 +422,7 @@ module MessageDequeuer
       it "gets a sender from the state and sends the message to it" do
         smtp_sender_double = double("SMTPSender")
         expect(smtp_sender_double).to receive(:send_message).with(queued_message.message).and_return(SendResult.new)
-        expect(state).to receive(:sender_for).with(SMTPSender, message.recipient_domain, nil, { servers: [endpoint] }).and_return(smtp_sender_double)
+        expect(state).to receive(:sender_for).with(SMTPSender, message.recipient_domain, nil, { servers: [kind_of(SMTPClient::Server)] }).and_return(smtp_sender_double)
         processor.process
       end
     end