Use the Thunderbird Search Bar
The quickest option is to use the search bar above your messages. Select the search field and type a person’s name, an email address, or any keyword that might appear in the message subject. If there are multiple matches, select one of the auto-completion choices.
Thunderbird Quick Filters
Select Quick Filter at the top of Thunderbird to see a list of search filters. Select one or more of the filters below to see all messages that match the criteria. For example, selecting Attachment shows all messages with attachments. To further narrow your matches, use the search bar beneath the main Thunderbird search bar.
Mozilla Thunderbird Advanced Search
Thunderbird offers more search tools to help you find the exact email you’re looking for.
Thunderbird Search Folders
You can save your search results in a folder so that you don’t have to search again in the future.