We often update blog content annually as our business is regulatory and changes are made frequently. However, despite redating the refreshed blog, it won't be sent out to RSS subscribers simply because it was updated.
The alternative is to duplicate the blog and set up a rel:canonical which is fine but rather sloppy from an SEO perspective, and in the end, the blog is better for us from an SEO perspective than the content is for us from a one-time email perspective.
