Thank you for the reply and a good question, so here we go.............
Apple send me invoices to a Gmail account which is one linked to AppleMail.
I looked at the Gmail original from google email web page and everything was there.
Preview, Print and save as 'pdf' all great.
From AppleMail I forwarded the apple email to my iCloud address and went online to open iCloud Web Page
Also forwarded the Gmail email over to the iCloud account as well.
So we now have two iCloud emails - one direct from Gmail and the one sent from the AppleMail
Result:
Looking at both of them we can see the whole email, try to print, Preview or save as pdf - All Blank and just prints a blank page.
Not even header of footer - just date , time & 'iCloud Mail'.
If we forward the Gmail email back from the google web page, then all ok.
So it's as if Google is cleaning it up and decrypting it for Apple.
Simple answer would be for Apple to email their invoices as pdf in the first place, instead of the silly 'preview view' which then need printing - Save as pdf as
they are at the moment.