Yes, the Shoviv Import EML to Office 365 tool does support exporting large EML files successfully. One feature that we can note is that it can transfer a number of EML files in one step which makes it well suited for large migrations. This tool also has an option of filtering that allow users to filter out items that can oversome the migration process and only allow the essential data. Also, it includes a preview option, by which, users can preview the EML items, before the actual migration thereby helping to check the data accuracy and reliability. It is built in a way that is capable of dealing with large numbers of migrations without a significant loss in speed or accuracy.