I use a product ThunderBird made my Mozilla as my desktop email client. They have a feature that allows me to attach a drawing to an email and then upload to Box.com which is very much like a DropBox. Then the email includes a link to the PDF file that I sent over to them instead of the file being attached with its large size.
What I like about this is that I only upload my final construction sets because everything else is usually smaller in size. Then I have the Box.com app on my cell phone so I am able to view the PDF files for all my construction document sets while I am out and about if need be.
And again free to a certain size but I have not had a problem.