Is this an IMAP account where the message bodies are fetched from the server on request.

I am using an IMAP Mail Server account. Apologies, but my technical knowledge is limited and I'm not sure if the messages are fetched on request. I can tell you that I recently replaced my hard drive, and when I opened Thunderbird for the first time since the new drive was installed, I did have to click on each folder to retrieve messages. At this point all messages have been retrieved and are displaying in the inbox and sub folders. Before the new hard drive, I was able to search message subject lines (no email body), but now even that seems to be disabled and search is proving to be useless. Any ideas?

right click the account and select settings In the synchronization and storage section for the account is keep messages for this account on this computer checked? In the Tools menu (alt+T) > activity manager is the program still indexing?

I see that folders are being indexed. Some have completed, but others are not shown, so I would assume this may still be ongoing. I found that search is working again displaying results found in message subjects, but still not in the body of emails. I will wait until morning to see if the continued indexing helps with searches within the email body. Thank you for your help. I will report back on the status tomorrow.

Sorry, I also did have to check the box to have messages stored "on this computer".

ok so an overnight might not do it, depend on the size of the mail account, the speed of the computer and what else is happening on the machine. It might take a couple of days to get everything as it was..

Got it - fingers are crossed. Thank you!