Amy Hoy, a veteran in the maker community, is really interesting to check out. She really advices people to use email marketing. I think if you use it well and add value it can definitely be a great channel.

for me, the prototypr.io newsletter is a massive part of the platform - i know people want it cos you can see hundreds of clicks ..I agree with Aiden - it has to add value

It is still relevant when you are providing value to your subscribers. I'm not very consistent with my newsletter but whenever I do I get responses saying it's really useful for them. I run community management newsletter @communitymanagerjobs.co

Pat (@patwalls) is running Starter Story, Raman (@ksaitor) is running Crypto Jobs List newsletter since long time and you should definitely talk to them to get more insights because they are consistent with it.

Also, there is Botletter which sends newsletter or content through Facebook messenger. You should try it out because these days more people tends to use FB for information and they might not want to subscribe to just another emailing lists.

Less and less effective because people get used to gimmicks, but if you have a strong connection with your audience it's worth it.
You control the timing and the medium.
Also you don't rely on Google/FB that could close your account anytime.