re :''Mine only show up if my Apple computer is on.'' The computer would have to booted up and Thunderbird running - how else would you see them. Perhaps you meant 'you have to be connected to the internet'. This sounds like you are using an imap mail account. Imap mail accounts see a remote view of the server. You have to actually connect to the internet so that the server can connect with Thunderbird to allow it to download emails. You subscribe to see folders. Then headers are downloaded and when you select an email, it is retrieved from the server and stored in a temporary cache to facilitate reading. The emails are not stored in Thunderbird, they are stored on the server. If you want a copy in Thunderbird profile folder to view in either Thunderbird offline view or if computer has no internet connection then you need to synchronise folders for offline use. This would get a copy into Thunderbird Profile folder. See info on synchronising: https://support.mozilla.org/en-US/kb/imap-synchronization#w_configuring-synchronization-and-disk-space-usage File > Offline > Download/synch now Once done you will now be able to see emails when offline or not connected to interent. Obviously, you will not see any new incoming emails until you go back into online mode. If you create folder on the server or in Thunderbird, you would need to subscribe to see it.