Since I’m impressed at the rate at which Posterous is introducing new features, I decided to stick with my Posterous blog and see how the platform matures. However, I wanted my Posterous to be a part of the Skeptic Geek website. It turned out to be quite simple.
1. Create Subdomain
From my BlueHost Control Panel, I created the sub-domain http://posterous.skepticgeek.com
Do not use any redirection.
2. Add CName Record
The CName Record should look like this:
posterous.skepticgeek.com. IN CNAME posterous.com.
In my case, BlueHost does not allow users to create CName records, so I raised a ticket to get it done.
3. Specify SubDomain in Posterous
In Posterous site settings, add the subdomain name.

Done!


