If it was me, I’d start by dropping the printed newsletter.
You simply tell people that 90%, or whatever is accurate, or your subscribers receive the newsletter electronically and that the time-suck of producing a printed version isn’t worth it.
Then, as Sean has suggested, put it into a membership site online.
Alternatively, you could charge those people who want a printed version for the cost of printing, packing and mailing.
Most people will understand that this is necessary.