eTransmit for Revit
It is not uncommon to have to share Revit model files as part of a milestone submission. If you have linked DWGs/custom keynotes it can be a challenge to put together all the files and keep the links properly pathed. There is a useful add-in by Autodesk that helps simplify this situation called eTransmit for Revit.
There are two different ways of accessing it depending on which version of Revit you are using:
2015 / 2014 / 2013 / 2012
You must log in to your Autodesk Account. On the left side you will see a bolded Product Enhancement link that will then take you to a long list. Once there you can CTRL+F type eTransmit and select your appropriate download based on your version.
Available through the App Exchange (must be logged in with a valid subscription account).