As a Thunderbird and K-9 user this is 51% good news and 49% possibly bad new. Good news because it should increase the chances that the two products will live a longer life. Possibly bad news because I'm one of the crowd that went back to K-9 5.600 because the new version destroyed the UI that was the primary reason why we picked K-9 over other apps. 100% self selection bias here. There was maybe an ongoing effort to…
May I ask what Thunderbird local storage means? Does that mean that emails are delivered and stored on the device, vs on a cloud server?
If you keep your desktop on 24/7 as many people do, then you might keep your email client (thunderbird) open in the background, checking for mail every 5 minutes so you know when you get new email. Since your storage quota is only 250mb, you delete email from the server automatically on download. Now suppose you want to take an email with you to a community meeting. You can print it out, or you can email it to yourself at a different address. Or if you were able to link up your phone with your computer's storage, you can just search up the email on demand, find related messages, and make changes to drafts for your community mailing list.
If you could connect to thunderbird with an IMAP client, then this would be possible.