Thank you to cketti and everyone else who has helped keep K9 going for all these years.
After using Gmail for nearly 20 years, I recently migrated to more privacy-respecting mail solutions and I was disappointed to discover that so few FOSS solutions exist for Android. I had last tried K9 sometime around 2013/2014 and could not see past the dated UI and functionality. I was pleasantly surprised to see the new design and features this year, as well as the Thunderbird project announcement. Kudos to all who have made this happen.
FOSS development can be such a thankless job at times, even more so where email clients are concerned. Just know that your work is truly appreciated by many, many people. I look forward to seeing where things go from here. All the best!