TIL that you can’t follow a Tumblr from one of your secondary Tumblrs. This puts a serious wrinkle in my previous recommendation as a replacement for Twitter.
Want to know when I post new content to my blog? It's a simple as registering for free to an RSS aggregator (Feedly, NewsBlur, Inoreader, …) and adding www.ff00aa.com to your feeds (or www.garoo.net if you want to subscribe to all my topics). We don't need newsletters, and we don't need Twitter; RSS still exists.