I use an excellent open source CAD package QCAD which I pay about 49$ P.A. to have the latest version for both Linux (home) and Windows (work).
Under Linux it can export as high quality PDF using the “File ==> PDF Export” function but the size of the PDF is quite large (about 2.9MB for my reasonably simple rear deck plans).
Another option is using the “File ==> Print” dialogue and selecting the “Print to File” option. By specifying either a PS or PDF extension you get files of 1.5MB and 253K respectively. The PDF generated is smaller and is more suitable for emailing.