I run Thunderbird 115.6.1 on a Mac OS 14.1.2 with 2 POP email accounts and 3 IMAP Gmail accounts. One active POP account had a large number of emails going back several years. Suddenly I noticed all but emails received in the past 3 hours had headers only, no data or attachments. My other email accounts were fine. Of course when I did a repair on that email account, the headers all disappeared as well, leaving me with only the latest 3 hours of emails and a lot of missing emails and attachments. What is the best way to recover the missing emails? If the data still exists on the hard drive how can I find it and can it be re-indexed? How can I restore the data file from one of my backups? If I get it restored, can I merge the emails received between the time of the data loss to the current emails, with the recovered data? Is there an email recovery program to handle this? For several days leading up to the data / index file failure I noticed that Thunderbird, when processing that one large email account was taking a lot of time to do simple tasks, likely spending a lot of time trying to figure out the index chains.