There are two ways for a nonprofit to send out their newsletter: by email or through the mail. (There is also social media, yet it is not effective.)
Most people use email because it is easier and cheaper. Also, the recipients can more easily forward the newsletter to other people making a wider distribution possible. However, I think the opposite happens.
Most people are flooded with emails and do not delete or manage their inbox. The newsletter email can soon disappear to the bottom of the screen and be forgotten. Even if opened, the email is scanned with little retention of the contents and few emails are forwarded.
By mail, the newsletter is time consuming and costly. Yet, I think there is a greater chance for someone to read and distribute it. A printed newsletter can be left on a table or counter, handed to other people, and kept for future reference.
The other advantage of printed newsletters is they can run four pages with pictures. An email should be no more than one page and imbedded in the email with no attachments or pictures that can easily distort the email format.
The purpose of a newsletter is to communicate what is happening in the nonprofit. Once written, it should be distributed as wide as possible and presented in a way to encourage people to read it. The more people reading the newsletter, the more people who would support the mission.
Of the three newsletters I’m involved in, two are distributed by email and one by print. I have not talked to many readers for any of the newsletters, but I have talked to enough people and found that more people read the printed version than the electronic version.