To setup the MP to use envelopes continuously without the need of selecting the paper size, we need to default the MP tray to size 10.
-From the printer dashboard, select paper size selection button > MP tray, SIZE 10 > Envelopes >Power cycle multi function copier.
Please note, this has to be performed physically at the printer without the web interface.
Also every time they use the MP tray with something other than size envelopes the printer will generate a query, prompting the user to select the size of the paper.
It can only be default to one size of paper per tray.