How to search a specific mailbox in Mail ?

If your favorites bar is hidden, it should show when you start typing in the address field. You can select a mailbox to search from there. If a particular mailbox is not in the favorite bar, drag it up to the bar from the sidebar. To always show the favorites bar and to make changes to it, click view in the menu and choose Show Favorites Bar. It will appear above the message pane.

You can alos type the Mailbox name in the search box and one of the options should be Mailbox contains: <your search term>. Select that, then go back in the search box and type the term you are looking for.

When searching, it will try to match the term with categories, like people, subject, etc. If you know you are looking for something in the subject, you can start with, "subject: <search term>"

Note that it wants lowercase and needs the space after the colon.

I find the help files to be very basic. If you do a google search on what you are looking for, you will get much more detailed help from many different sites including Apple Support documents and even from the Apple forums.

Last time I looked, there was a whole page on searching including how to use the search tokens as I pointed out above. I'm not logged into a 10.8 system to check that out right now, though.

What I also found when playing around with it was that if it couldn't find a match in the selected mailbox, it reverted to All, otherwise, it would default to the selected Mailbox, with the ability to select All in the Favorites bar. However, I'm not sure if that was just some weirdness that happened.

Mail Help - type in search messages in mail

If I type search messages in mail in the Help search box (top right) I get the below results.

You'll get that if you type "how do I search for text" or just "search" or just "find"

At the top level, under Essentials, Search Messages gives you the same as the top hit on Eric's search.

The answer to your original question in the post is given in number 3.

If needed, change your search to vary the results:

Search a specific mailbox:	Click a mailbox in the Search bar. To search a mailbox that’s not shown, start typing a mailbox name in the search field.
Search several mailboxes at once:	To search mailboxes that aren’t shown, start typing a mailbox name in the search field, choose the “Message contains:” suggestion, and then choose Mailbox from the token’s pop-up menu. Repeat for each mailbox. Or select the mailboxes in the sidebar before starting your search, and then click Selected Mailboxes in the Favorites bar.

Why is "Search a Message" and "Search a Mailbox" not intuitive?

If I want to find something inside a single message, I would choose "Search a Message."

If I wanted to find a particular message I would choose "Search a Mailbox"

Or, I would type, "find a message" or "search for messages" in the Help search field and the top hit would be turns out to be the answer.

Or, even simpler, since "Search Messages" is the only main item referring to "Searching," I would start there. In that case, it goes right to what you want.

If I really wanted to know about searching for text in a particular message, I would first scroll to the bottom to see what was offered as related topics. Lo and behold, there is a related article that discusses searching in a message.

However, the help files in OS X are not very robust. They never have been. The Macintosh Way is all about trying things out and see what happens. You can always undo (most of the time).

But for people who need to read a book, David Pogue makes a ton of money publishing the Missing Manual series.

Send Apple feedback. They won't answer, but at least will know there is a problem. If enough people send feedback, it may get the problem solved sooner.

Feedback

It takes to many clicks to find the information. It should be more accessible.

It's right on the front page of Mail Help.

If you start typing "Search" in the Help menu search box, several options, including that one are offered:

What "View" are you talking about? I can't find anything about searching under the View menu, or in the View Mail help topic. Sure it will take just about an infinite number of clicks if you are looking in areas having nothing to do with Searching.

I'm not sure it is possible for me to help you.

That's not what my Mail Help looks like, but still, not an inordinate number of clicks, nor is it non-intuitive to look in View messages to find Search features.