Side mailbox area in disarray

Question

I just imported mailboxes using Eudora mailbox cleaner from TBird to Mail, but the mailboxes aren't arrayed as I would like.
If someone could tell me how to add a screen grab to a message here, I could better explain my problem with a picture...

Answer 1

You’re welcome.
You appear to be confused by the names of the mailboxes. The imported mailboxes are named that way simply because that’s how they were named originally, but imported mailboxes are like any other custom mailboxes you might create manually yourself and have no special meaning as far as Mail goes. You can rename the imported mailboxes if you wish or move the messages they contain to the predefined account’s Inbox, Sent, etc. if that’s where you want them to be.
Here’s a more thorough explanation of how mailboxes are supposed to appear in Mail:
1. Instead of grouping mailboxes by account, Mail groups mailboxes by purpose first, regardless of whether they are stored locally or on the server, then groups by account the mailboxes that don’t serve a specific purpose in Mail. If you have more than one mail account, each has its own Inbox, Drafts, Sent, Trash and Junk mailboxes, which appear under the respective group showing the account name instead of the real name of the associated mailbox in the filesystem.
This has the advantage of letting you choose at any time, and independently for each mailbox, whether you want to look at your Inbox, Sent, Trash, etc. mailboxes as if you had just one of them shared by all accounts (i.e. an aggregate), or look at each of the corresponding individual mailboxes separately.
2. Each mailbox under a pre-defined group is associated with a mailbox in the filesystem whose name may or may not be exactly the same as the name of the corresponding mailbox group. By default, the name of the actual mailboxes in the filesystem associated with Sent and Trash, for example, would be Sent Messages and Deleted Messages, respectively.
3. The association between a mailbox in a pre-defined group and the actual mailbox in the filesystem is fixed for POP accounts, but can be changed for IMAP accounts by means of Mailbox > Use This Mailbox For or the corresponding Preferences > Accounts > Mailbox Behaviors > Store messages on the server setting.
4. Mail may defer the creation of a pre-defined mailbox until actually needed to store messages there. Also, in some circumstances Mail may be unable to create or locate the actual mailbox in the filesystem (see #10 below for an example), but the association does still exist in those cases from a logical point of view, even though Mail may be unable to display or store messages there.
5. Each and every mailbox appears once and only once in the mailbox list, be it (1) under one of the pre-defined groups with an icon that conveys its purpose and the name of the account it belongs to (if you have more than one mail account), or (2) with a generic folder icon and the real name of the associated mailbox in the filesystem if it serves no specific purpose as far as Mail goes. Under no circumstances can the same mailbox appear both ways; it’s either one or the other, depending solely on whether it serves a specific purpose in Mail or it’s treated by Mail as a generic mailbox like any other.
6. By itself, the name of the mailbox is no indication of whether it serves a purpose in Mail. If it appears in Mail with a generic folder icon, then as far as Mail goes it’s a generic mailbox like any other, no matter what its name.
7. For IMAP accounts, a mailbox with a generic folder icon can “disappear” and become associated with one of the pre-defined groups as a result of changing the corresponding Store messages on the server setting in Preferences > Accounts > Mailbox Behaviors or doing Mailbox > Use This Mailbox For on it (server-stored mailboxes only). This, in turn, would cause the mailbox being previously used for that purpose to become dissociated from the corresponding group and “appear” as a mailbox with a generic folder icon.
8. In addition to the account-specific mailboxes that appear with the account name under each of the pre-defined groups, Trash and Junk may also have an “On My Mac” mailbox. This is where messages deleted or marked as junk are moved if they were previously stored in a custom “On My Mac” mailbox or in a locally stored mailbox associated with an IMAP account (i.e. a mailbox for which Store messages on the server has been turned OFF in Preferences > Accounts > Mailbox Behaviors).
9. Generic mailboxes that don’t serve a specific purpose as far as Mail goes (i.e. mailboxes that appear in Mail with a generic folder icon), appear below the pre-defined groups. In principle, “On My Mac” mailboxes (i.e. locally stored custom mailboxes) would appear as top-level folders, whereas server-stored mailboxes would appear grouped under a globe icon for each IMAP or .Mac account. However, if there is no need to differentiate between “On My Mac” and server-stored mailboxes (e.g. because you only have one IMAP account and no custom “On My Mac” mailboxes), Mail will display the server-stored mailboxes as top-level folders instead, just as if they were “On My Mac” mailboxes.
10. Some IMAP accounts use a NAMESPACE feature that Mail doesn’t handle properly and that causes server-stored mailboxes to appear as subfolders of the account’s Inbox, even though they really aren’t — see “Can't create folders, only subfolders of INBOX” in the Courier FAQ, for example. Those IMAP accounts require INBOX to be typed in Preferences > Accounts > Advanced > IMAP Path Prefix for Mail to handle them properly.