I'd hoped this question was answered at https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer, but that article assumes a Mac-to-Mac migration, and it doesn't work for a Windows-to-Mac migration. The discussion at https://support.mozilla.org/en-US/questions/1324908 addresses the issue, but what the poster did to get things working is rather vague ("I took more from one [response] and a little from the other two...]. Can someone please summarize or point me to a summary of what needs to be done to move the files in a TB installation on Windows 10 to MacOS 14 Sonoma so that the installation on the Mac will work like the one on Windows did? I have a lot of old mail, so my TB directory is over 40 GB. Copying it from my Windows machine to my Mac (either over a network or via a USB drive) takes quite a while, so I'm trying to avoid any more trial and error than I've already gone through. Thanks. PS - I apologize for the use of raw URLs above, but I was unable to figure out Mozilla's markup language, and there's no preview button for posts, so I decided to go with something I figured was unlikely to get mangled in the publication process.