The Bundle Mails feature of tZirr allows you to select a set of mails and save them as Personal Storage Table, popularly known as an PST extension file format proprietary to Microsoft. You send it as an attachment or you can save it for later as an archived file. For this you need not select an entire folder; you can create neat little bundles of mails. The search result based on your specific criteria can be bundled even though the mails are across folders.
Also CSV is created for mails that are bundled for reference before opening the stored PST.