Hope someone can help..... Over the past year our sitemap has grown and grown to about 1.8m pages, and Google indexed pages averaged around the 3-400,000 mark but recently that dropped to less than 1000??? no mapping issues our changes?? any advise?
1st question from me would be - Are your 1.8 million links on your site map spread over many numbered pages?
i think this time google doing some change in his Algo so i think that's why this problem you facing otherwise can you give you site link or sitemap URL so i will analysis about this problem and i will give you good reply.