We can always use .pdf format it is open and any person receive it, no need to by Windows Operating System or MS Office just to open it. If we use .pdf it can be open on Linux, Mac and in Windows as well and even most of the smart phone now has ability to open pdf.
Alternatively use openoffice (OpenSource office suite) it is available for Windwos, Linux and Mac as well. It uses open format like .odt. Its storage specification are open and any application can easily add support to open it without paying anyone any royalty. Unlike .doc is proprietary format its specification are not open so no office suite can offer to open it, and with hack to .doc they cant give proper support for .doc.
Communication standards must be always open without dependencies on particular company's format, Think for a language we speak, if we need to pay royalty to some company for each word of language we speak then what will happen? .doc is Microsoft proprietary format.
Might be it will difficult for people to switch to openoffice, but atleast everyone can use feature provided in openoffice, i.e. export to pdf. So you can open your document, export it to pdf and then send it via mail. (http://download.openoffice.
"www is open standards that why we can open any html page with any internet browser or any application on any OS. Anyone can implement it as it is open standard"
"At least we can start with using pdf for communication"