[efreak]

It sounds like they want k9 to be a client for thunderbird, so when you read email in k9, thunderbird marks it as read; when you fetch email, it goes through thunderbird. Thunderbird would be a caching proxy as well as an email client.

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.