I slowly lost some of my email functionality over the past year and just didn’t have time to fix the problems until now.
The first problem was no longer being able to use Thunderbird for updating my offline Mbox format email archives for my job. I handle all current email, work and personal, via web clients. But for long term storage and future readability nothing beats Mbox, my archive goes back to 1997. My client of choice for my Mbox archives is Thunderbird.
Over time as the security for Office 365 tightened I stopped being able to connect and move current mail to the archives. I’d searched a bit for solutions but all I found either didn’t work or was too insecure for me. Today I looked again and found these great instructions. Configure Thunderbird for Modern Authentication and MFA
The other problem was with my first custom IoT device, a monitor for the basement dehumidifier. My cable ISP provided an IP secured SMTP server since the beginning but over the last year it slowly has been changed. This meant the daily status, and water collection tray full, emails were no longer working.
I’ve settled on the App Password solution for my custom Python code as described here: G-Mail and less secure sign-in technology – Raspberry Pi Forums. I would like a more secure solution but so far I haven’t found one that’s free.
Paul Hutchinson's Blog 