Mozilla Thunderbird Email Client – Part 2: Corrupted Inbox

In a post I made back in July 2007, I switched from Outlook to Thunderbird for my email client. I’m still 100% happy with that decision.
However, over the past few days I’ve experienced a lot of problems with Thunderbird. Yesterday it was so bad that it basically just trashed the hard drive all day and was unusable. I did some searches on the Thunderbird support site and came to the conclusion that my inbox was corrupted. I tried deleting the index file for my inbox and then restarting Thunderbird. This is supposed to rebuild the indexes, which it did, but it did not help my problem. I tried several more things and then left it re-indexing again overnight. It was still churning away this morning and still so slow it was unusable.
I searched through more FAQs and articles and put together this sequence to fix the problem.

  1. Unplug my Laptop from the Internet.
    Start Thunderbird.
  2. As soon as Thunderbird starts, tell it to work offline by selecting File | Offline.
  3. Right-Click on my Inbox and select Compact.
  4. After compacting was successful, switch back to online mode by selecting File | Offline and unselecting offline.

This fixed the problem.
Why did this happen and what did the fix do?
Because most people, including me, get a ton of email in their inbox and then either delete it or move it to other folders, the inbox can become corrupted. This deletion and moving creates hundreds, or maybe thousands, or even tens of thousands, of messages in your inbox that are marked as deleted (you can’t see them anymore) but they’re still in the file that makes up your inbox. It leaves holes so to speak. Compacting is the process that actually removes those messages (holes) and shrinks your inbox file down to the size of just the messages you have kept. Actually, I think it probably copies the active messages to a new inbox file and then deletes the old one when it’s done.
You should either set an option to automatically compact your inbox from time to time, or manually do it once a week or so.
You should also either set the option to empty the trash when you exit or empty your trash (and compact it too) about once a week or so.
There are more complex procedures in the Thunderbird support section for corrupted folders that you can’t compact. You can find that info here:
If an email is important you should move it to a folder besides the inbox. This is because the inbox is more vulnerable to problems. This is true in most any email client application, not just Thunderbird.
Until Next Time,