Email v. blog posts
I have long been an advocate of replacing many types of email with blog posts. I still think this is the correct approach in many situations, but their does seem to be a fundamental difference in writing email and writing a blog post which has everything to do with the audience.
The smaller and more highly trusted the people on a particular email distribution list, the more likely you are to write quickly and off the cuff, with less sanitizing of the message. The broader the distribution list and the greater the potential career impact of the people on that list, the longer you are going to spend composing and polishing that email. It's a fundamentally different sort of communication than the first email.
Blog posts are much more like the latter. Even if only a few people actively read what you write, the potential for lots of people with lots of influence to do so is there. This may be a contributing factor in me writing a lot more emails than blog posts. I certainly don't want to get fired for blogging.