I love arguing on the internet, but my favorite blog online is The Daily Dish. It's Andrew Sullivan's blog. He does take emails, and he routinely posts reasonable dissents. I love that model. It allows for feedback while avoiding the typical internet trolling.
If you want to send me a dissent via email, feel free. I may ignore it completely. I may never post it. If it's a persuasive argument, and I change my viewpoint, you deserve to be heard.
If you've got something that you feel absolutely deserves to be posted, feel free to write it yourself, distribute it, take it to Congress, and make it public policy.
Thanks to those who initially commented, both negatively and positively, on my older posts.
Feel free to email me with dissents or assents at firstname.lastname@example.org.