“joekewe” posted this fantastic tip in response to Macworld’s article titled “More flexible Mail searching“:
More complex searches are easily accomplished in Mail.app for free.
Choose “Entire Message” then you can enter: [search string] [from:sender] [to:recipient] [subject:subject] in the regular Mail search box. Probably enough for most needs without switching apps.
Note that the [brackets] represent optional criteria. Do NOT type the brackets, and don’t forget to choose “Entire Message” or it won’t work.
You can select “this” mailbox or “All Mailboxes” to search as usual. No need to spend $30 and switch applications for this functionality.