That's curious. The presence of your old Inbox file in the Recycled folder suggests something that's happened at file system level. Thunderbird would have put it into its own Trash folder.

In your file manager, you could simply copy the Inbox file (maybe you should rename it first) from your Recycled into the Local Folders folder. Then it and its contents should appear in Thunderbird.

Please consider filing your messages. Statistically, Inbox suffers more corruption than other less-frequently-used folders. IMHO it's not a safe nor suitable place for long-term storage.

Every new message that comes in has to be appended to your single large Inbox file, and its index file Inbox.msf rewritten. That's a lot of data being unnecessarily processed. Unless, perhaps, you're using the experimental maildir format.

Thanks very much for your suggestions. Firstly, I checked in my live profile for any Trash folders, and found two "Cache.Trashxxxx" folders with just 13MB in each so I assumed these are too small to contain my missing emails.

I then closed Thunderbird and restored the Inbox from my Recycled bin, and renamed the existing Inbox to "Inbox.new" to protect it. Happy days...all my missing emails have returned! I have no idea how it was partially deleted but I'm delighted to get them back.

I think you're right about not keeping emails in the Inbox. I have let my Inbox grow to become much to large. Over the last year it has become corrupted several times meaning I could not search and had to rebuild the index file. Recently, I have been deleting and filing emails to make it half the size in the hope this will help. I will now work harder to reduce the Inbox even further. And I will start to take backups of my profile, which I have not been doing.

Should I be equally concerned about my 400MB Sent folder and move these email to a Local Folder? Any other good housekeeping tips to avoid future disaster?

Many thanks

I wonder why people keep all mail in INBOX and also don't compact. Why are they not using the local archive-function (nor archive them on server)? My first thought before trying that was that it would be hard to retrieve. It wasn't! Archive are ordinary folders stored under Local Folders. The only drawback is that you cant access it from other units.

I treat my Inbox and Sent as "to-do" places. I aim to keep them empty. Messages that I want to keep will be filed according to the correspondent or topic. I keep related incoming and outgoing messages together so that I have a full record of a conversation all in one place. I use an add-on that prompts me where to save a sent message, and if it's a reply, then it's normally already in the appropriate folder.

In many cases, I use filters to automatically put incoming messages into appropriate folders, so, for instance, notifications for replies to this website, or to the mozilla newsgroup go straight into my "mozilla" folder.

The flip side to this is that I need to jump between folders a lot, and I suspect this is what deters many people from using folders. However, View|Folders|All, or a Saved Search configured to collect unread messages gives me a simple way to catch up on all the unread mesages regardless of their location.

Anyhow, that's how I avoid large accumulations in either Inbox or Sent.

(And then when I handle email on my Android devices, it becomes clear just how restrictive and limited their email clients are.)

Hi Gnospen,

Thanks for your advice. A few weeks ago I had about 16,000 email in my Inbox dating back to 2005. Plus I have a few local folders with several thousand emails. When prompted I have been compacting the Inbox.

Now I have deleted half of these emails and archived most of them to local folders using the Thunderbird "archive" feature, with folders created automatically for each year (2005, 2006...etc). I now have just 3,000 emails in my Inbox - much more manageable.

I experienced the same problem. I performed a repair on the inbox folder (right click/properties then repair folder) and all the emails returned - thank goodness for that. I'd have been mightily annoyed if Thunderbird had lost all my emails.

I have since divided my inbox into yearly-based folders. Hopefully it won't happen again.