It is best to create a PDF first and then email that as an attachment. Another choice would be to create a .psr file which is a true representation of the datawindow. But that requires the users to have a psr viewer (that you would build into your application.) Another choice is a windows metafile.
You can export the DWO source and its data and email it- however, the receiver would need either PowerBuilder or InfoMaker to reconstitute the DW presentation layer. The PDF form of the DWO & its data of course is readily transportable.
Note that you could also use the PSR Viewer approach as another alternative (check out the SaveAs(PSR!) command in the PB Help.