These days communication between investors of the projects and the design offices through the Internet is more and more frequent.
However sending emails (with files enclosed) is only one and quite limited way of communication. We cannot suppose, in general, that our client would have any CAD software installed on his PC, which could give him the possibility of checking the drawings sent by you - for example in DWG format. Yet you often need an immediate response or approval from your investor and so on.
For this purposes format DWG (drawing web format) and Express Viewer programme by Autodesk are available. This way it is possible to check all drawings through the Internet Explorer, including zooming, shifting, work with layers and printing. It is sufficient to have plug-in installed on your Explorer (cost-free). Opposite the above mentioned alternative we can suppose the investor's having Explorer on his PC enabling him checking the saved drawings easily.
In case you do not know whether your browser supports DWF format click on this small sample drawing (29 kB). If your browser supports DWF files, you will see, in a new window, the cutout of the drawing. If not, then this cross-reference (= xref) will be taken by your browser for the classical tag on a file and it will offer its saving on the disk. Then you might install the above mentioned programme.