It depends on how you saved it. '''File|Save As''' gives me three options: * '''file '''will save it as an eml file outside of Thunderbird. It would have asked you where to save it; * '''draft '''will save it internally as a draft, in your Drafts folder. It will be in the Drafts folder of the account you were using at the time; * '''template '''will save it internally as a template, in your Templates folder. It will be in the Templates folder of the account you were using at the time. If you can recall any specific words you used in it you may be able to find it by using the Global Search.