file size

The process below may help:

Open your PDF file in Preview, and select: Export from the File menu

Then select "Reduce File Size" from the Quartz filter drop down menu. Change the name of the file at the top space to avoid overwriting the original PDF.

I have reduced a 10 MB file to just over 1 MB with no noticeable difference in quality using this process.

Were you compressing it in the Finder?

That should not affect quality.

Still might be difficult to get it down that far, I just zipped/compressed a 10.8 MB PDF & the result was a 10.4 MB ZIP.

You'll have to find another way... if you posted the 5.5 MB one online somewhere & emailed them the link, could they download the PDF then.

Besides, sending a 5.5 MB attachment in any Mail App would make it anywhere from 7.7 MB to 11 MB.

When you scanned the document(S), do you recall the resolution you had set for the scan? I would think a scan of 200, or 300 ppi would give decent results.

My example above was from a PDF file created within PrintShop, so the amount it was able to be shrunk by the quartz filter export may differ from a scanned file, but I must say I was most impressed by the amount the file size was reduced, and the quality.

You can try Right clicking on it & choosing Compress to see if the resulting .zip is smaller.

Bring the DPI down to 100 PPI & that will not only be smaller, but should be clear on the screen without condensing the PDF