I noticed the last weeks that Google doesn’t index all my Posterous pages and that while I point my blog Prime Blogger to a .com domain name. My first idea was a missing Google Sitemap. I tried before to add my Posterous site to my Google Webmaster Tools account, but this requires a custom meta tag on your homepage or you need to upload a unique file to your site to proof the ownership. I suggested a function for a Google Sitemap to Brett from Posterous  and he gave me the hint that I’m able to change the HTML using a custom theme and yes this is key to get your site accepted in your Google Webmaster Tools account.

Submit your XML of last 20 Posterous Blogs as a sitemap to your Google Webmaster Tools account. The article explains how proof you Posterous site ownership.