in-house civicrm install - but remote email install?
you could have a look at an extension called CiviProxy we developed a while ago. The major focus is on security as it enbables you to run CiviCRM without having to make your environment publically available.

However, most interesting for you is probably the fact that it enables pass-through of tracking data on opening and click-through rates as well as Sign-on and off of your newsletter (Webpage templates).

Please find more information on the github page and in this recorded video presentation.