Finding folders in Mail

If you are just looking to view all the messages in a particular mailbox, type the folder name in the search field. Look for the mailbox list and the folder to appear in the mailbox list. Select it and it will show all messages in that mailbox.

If you want to see the path of the mailbox in the finder window, open a finder window and go to your user library and select the Mail folder. Type the mailbox name in the search field and look for the folder to appear in the list. Right Click on the folder and choose Reveal in Finder. A new finder window will open showing the complete path to where that folder lies.

You use to be able to click on the mailbox name in a message and the mailbox would be highlighted in the sidebar. This does not seem to work in Yosemite. I have a lot of mailboxes and many are buried within other mailboxes. There must be some way to easily find a given mailbox in the sidebar but I can't find one. I can search a mailbox name and it will show me all the messages in the mailbox but it won't show me where the mailbox is. Frustrating.

Mine show up under the Mailboxes search token.

Perhaps you need to re-index Spotlight: Spotlight: How to re-index folders or volumes - Apple Support

But, that just allows you to search that mailbox.

If you have all of your sub-mailboxes disclosed, you can select a mailbox and start typing the name of the desired mailbox. To select, you actually have to go into the rename mode by single-clicking the name, then typing esc to exit rename. It will highlight the Mailbox and you can then type mailbox names.

See if you can find the file using this program. If you go Finder/View/Show Path Bar, it will show you where it is located.

EasyFind – Spotlight Replacement

You might want to consider starting a new discussion. Since this one is marked solved, less people are likely to look at it. You can link to this one.