Inkjets probably use the computer to render the print job anyway, so it is computer memory that is used rather than printer memory.
(The test page that would tell you is not the windows one - that just tests printing and shows what drivers windows is using - you would need the printers own test page. You may be able to get it from the printers menu if it has a display.
(used to be easier when you just turned it off, held down the "on line" button and turned it back on!)
Technology is getting a bit beyond itself:-(
Using a browser other than Firefox works and may be a clue to the problem. There is also an issue over sending format. Jpeg has never been a problem. These attachments arrived as .pdf but saved as Firefox HTML (all Greek anyway)
It used to be that to view a PDF you needed to install PDF software like Adobe reader or Acrobat Reader as it was. Lately web browsers of all flavours have started shipping with PDF rendering capability built in, and the likes of Edge seem quite aggressive at setting themselves as the default PDF reader app on the system. They do tend to differ in performance somewhat. Not always giving exactly the same capabilities, and some using more system resources than others.
I tend to find when it comes to printing etc, the browser based options tend to be somewhat less capable than the dedicated PDF applications.
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