Patreon did a study

[Aloria]

You can use a newsletter to give updates on what you are working on, and maybe point people at other artists whose work you follow.
That's also an opportunity to network with other artists and give each other shout-outs.
I feel like newsletters really serve both purposes: they are marketing, yes, but also networking opportunities.

yeah, but again, I don't have enough to say every week other than
still working on arc 4 of soulless prince. I'm depressed again so I haven't even opened the document in 3 days. (: 

I just don't think anyone wants to have that in their inbox.