I am moving from Thunderbird to Mac mail on my iMac running OSX. If I uninstall Thunderbird will the local folders I created in Thunderbird remain on my computer for importing later? I don't want to bring all of them over now, but would like to have the option of doing so at a later date. I don't want to uninstall Tbird and then have the local folders disappear.
All your Thunderbird data, including the local mail data is stored in the Profile folder, located either at
Deleting the Thunderbird app won't delete any of the data there, unless you use a 3rd party uninstalled app like AppZapper. You can of course make a manual backup of those folders for added safety.