Too many URLs

Hi there,

It seems that if your site has over 50,000 posts, google will not accept the sitemaps coming from your site unless each of the sitemaps are <50k urls. I have tested this out through Google Webmaster Tools and manually chopped them into two smaller files and google took it in without a problem.. but that’s manu process. Can you please fix this ?

Here is the exact message.
Too many URLs
Your Sitemap contains too many URLs. Please create multiple Sitemaps with up to 50000 URLs each and submit all Sitemaps.

Thanks