Searching for messages
You are able to search for messages in the top level of folders or just one particular folder, thunderbird will not allow you to search in two pre selected folders.
1. Click into Edit > Find > Search Messages.
2. Use the drop down list, labelled Search for messages in, to indicate the folder that you wish to search in. Either search in a specific folder such as Inbox, or search through a folder tree by selecting the top level folder.
3. You can change the first field to search for text that appears in the body of a message, or by its sender or date.
4. You can change the second field to search for messages that contain a specified word or phrase. If the list is too general you can click the plus button to add additional search criteria.
5. Click search to begin searching for messages that match your criteria.
6. Some users may get the above error message while searching through sub folders, simply click ok to the message to complete your search.