Documentation says: "According to the Google Sitemap FAQ, your sitemap can contain up to 50,000 URLs or reach a file size of 10MB (uncompressed!). However, I would recommend you to split such large sitemaps into various smaller ones which allows Google to retrieve only the latest ones regularly. This will save you a lot of traffic."
I have a few sites with > 50k files, one with over 400k. How do I use the plugin to create multiple sitemaps?