If you just want to do that once, or occasionally, you can simply copy the messages in your gmail inbox to a new folder you create under your "Local Folders", and then delete them on the server. (first part will take some time, though) After that, to always copy new messages to your folder under "Local Folders", you could set up a message filter for your gmail account that just copies all new messages to your local folder. (Tools -> Message filters). Once you're confident that the filter works, you can start regularly deleting messages from your gmail inbox (or even change your filter to directly move them to the local folder). But keep in mind that then the only copies of your messages will exist on your local disk. So if there is any important stuff in that inbox, be sure to make regular backups.