I'm just a consumer of content, don't produce anything that I try to market. But I can tell you that there are very few things I want to be notified of. I don't say this to be mean or anything, just trying to give you a data point.
In my case, I can list the things I want to be notified about off the top of my head:
1) When matt colville posts a new video to YouTube (but not when he streams on twitch).
2) When KickStarters I've backed post an update.
3) If there's a new version of a PDF I've downloaded from DMsGuild or drive thru RPG.
4) When someone replies to me in a forum thread (like on here or RPG.net, but not reddit).
And notifications have to be pretty infrequent. If they happen too often, I'll block them, regardless of how much I may have wanted them to begin with.
The thing that makes me happy to see a notification is when there's something I've been anxious for in it. So I guess generally, I'm not interested in notifications I didn't actively seek out. I view them as a tool for me the consumer, not as a tool for the producer.
So in your case, for me to want notifications for your mailing list, I'd need to have seen stuff in it before and been impressed enough that I'm excited for the next one to come.
I don't know if that's helpful, and I really wasn't trying to be rude or dismissive or anything. I just thought it was an interesting question.