''<p>Richard403 [[#question-1494944|said]]</p>'' <blockquote>I am currently using Thunderbird 115.3.1 (64-bit). The about info shows that I can update to 115.10.1, however, I believe there are much later versions but I don't know if I can update to the latest. My MacOS is 10.15.7 and that is the latest I can install. I have a large amount of email stored on my MAC and not in the cloud. I want to be able to access these emails that are on my hard drive, in addition to Thunderbird, in Apple Mail. I have researched and it appears that the best way is to export from Thunderbird is into the mbox format. However, there does not seem to be a way to do this in the version of Thunderbird I am using. How do I move all of my local email in Thunderbird to my Apple Mail? Thanks for any help, Richard </blockquote> Thunderbird and apple mail do not share an MBOX format and have not since mac mail V1. So you might want to reconsider your plan. Just to be clear, MBOX is the native storage format Thunderbird uses. However for those that are challenged by the file system and copying files, there is an addon. https://addons.thunderbird.net/en-US/thunderbird/addon/importexporttools-ng/?src=ss