Currently Being ModeratedJul 2, 2013 5:02 PM (in response to hotwheels 22)
1. It will only offer categories where the search term appears. If you spotlight index is flaky, you might not be seeing some options. I think a lot of people get really frustrated with the search function when their Spotlight index is not complete. You can use header names and such in the search by typing the header, colon, then search term. E.g. "subject: lunch" It likes lower case for tokens, and you need to put a space after the colon.
2. & 3. Not that I know of. However, you could go into the Finder, navigate into your Library/Mail/V2 folder and Cmd-F. Then you will be searching in the Mail folder (depending on your Search prefs in Finder). It will find messages and attachments.
4. The search location should be indicated (highlighted) in the favorites bar. I think it defaults to All, but you can choose any of the other things you have in the Favorites bar. However, it may switch to All if it can't find anything in the selected mailbox.
5. From what I can tell, if you select a folder in the ON MY MAC list, it will stop searching. You have to use the things you have in Favorites bar, but see the item in help about searching a mailbox.
I think the Help gives some good info:
You can quickly search messages to find specific text, messages to or from contacts, attachments, or more. You can search messages in all mailboxes or specific mailboxes, and save searches to use again.
If you use the Any token or search in all mailboxes, Mail finds messages containing words that have the same prefix, or the same beginning letters, as any of the words you typed in the Search field. The words can be in any order. For example, if you type “box” in the Search field, the results will include “boxcar” but not “mailbox.”
To include the Trash and Junk mailboxes, and encrypted messages, when you search all mailboxes, choose Mail > Preferences, and then click General.
For best search results for Internet Message Access Protocol (IMAP) and Exchange accounts, make sure the “Keep copies of messages for offline viewing” option is set to “All messages and their attachments” on the Advanced pane in Mail account preferences.