You can download eTransmit 2015 from your Autodesk Subscription account. Click Product Enhancements under Quick Links on the left, eTransmit for Autodesk 2015 is available as an extension.
Unfortunately this page is not searchable...and not the most user friendly...you can sort by a category (title, type or date)...the default is Release date in descending order. The release date was 2014-04-18
It may also show up on the Autodesk Desktop App.
