Troubleshooting WordPress Imports
Sometimes WordPress doesn’t properly encapsulate HTML within it’s XML export file, which is what Posterous uses to import your WordPress blog. To improve the reliability of the import, you can run your WordPress export file through Tidy, which can fix errors within the file.
1. To get started, go to Tidy and then upload your WordPress export file by clicking Choose file.

2. Select Input is XML
3. Click Full Report
4. Use the fixed export file in the Posterous WordPress importer to import your site