I need to email a PDF that is 40.1 MB. How can I decrease the MB to make it smaller?
No way with just the free Reader. It can be reduced with Acrobat, although probably not enough. It may be better to do all reductions -lowering the resolution of images for example- in the original from which the PDF was made, and produce a new one.
I have acrobat
Then start with File > Reduce size.
Or Save as ... Optimized PDF. I have recently reduced a 100MB scanned document to some 200KB.