How do I send a powerpoint attachment that starts when opened?

Answer 1

Open your PowerPoint presentation,
click on FILE and
choose SAVE AS,
then at the bottom of the box, by the "Save as Type" field,
simply select PowerPoint Show (pps).

When ever somebody double-clicks a PPS file, it automatically starts the slideshow.

If the receiver does not have PowerPoint installed, then you must use File / Pack 'n Go. This will convert your PowerPoint file so that anybody can see the slide show.

If you have later versions of PowerPoint, you may consider File / "Package for CD" as well.

Answer 2

Search the help menu for autoplay or self-running. You should get to the info from there.