Apple Mail’s stores it’s email in an unusual location…  You would think, since it is user created content, that they would be stored in ~/Documents, but for some reason Safari Bookmarks, and Apple Mail are actually stored in ~/Library.  By the way, the Safari content is in ~Library/Safari. Apple Mail emails are stored in ~Library/Mail.
Inside the ~Library/Mail folder you will find “Envelope Index”. Â If you find Apple Mail slowing down, or in Spotlight searches you start getting duplicate results, try deleting the Envelope Index (with Mail Closed, of course), and restarting Apple Mail. Â Apple Mail will then display an “importing” message, but that is normal…. Â I have seen no reports of any issues of data loss when using this method….
Duplicating the Mail folder, will allow you to take a snap shot of the mail, rules, and other settings, so that you can migrate it to another system (or just simply back up the data).
In the ~Library/Mail folder, you will find:
- AvailableFeeds – RSS Data
- Envelope Index – Headers for the Mail in a pre-compiled form
- Mail Folders – The Filenames are in the form -@. Â So a pop account for john smith on gmail would be named POP-johnsmith@pop3.gmail.com
- Mailboxes contain the mbox files that are not stored on the remote server
- Signatures – Stores the signature files for the accounts
- SmartMailboxes.plist – contains the query data for the SmartMailboxes
- MessageUidsAlreadyDownloaded – contains the high message mark for all the accounts (pop, imap, etc)
Hope this helps… Â If you would like me to expand on this, please feel free to ask in the comments…