IMAP account "standard folders"

Question

I've been following another Mail thread about IMAP folders that highlights my own confusion about the expected behavior while creating & maintaining an IMAP account.
Background: I created an AOL IMAP account in Mail, using the settings I found online for account creation. (There was no indication of a need for, nor have I entered, anything in the IMAP Path Prefix field.) This created an "AOL IMAP" inbox (in the inbox parent) & an "AOL IMAP" account group mailbox with (@) icon, containing four subfolders named as follows: Sent Items, Saved, Spam, & VOICEMAIL. There were no other mailboxes created by creating this account (no "AOL IMAP" mailbox in Mail's "Sent" parent or in its "Drafts" one.)
It is my understanding that the four subfolders already exist on AOL's servers for any AOL subscriber. They are all visible using AOL's webmail interface, although the AOL client software for OS X (unlike the Windows one) allows direct access only to Sent Items, which it labels "Sent Mail." (There is an "Old Mail" tab, but it is in effect only recently read "inbox" mail, & has nothing to do with "Saved Mail," which the AOL client doesn't support.)
All four of these subfolders are supported by Mail.app. However, since all are created as subfolders in the 'group account' I gather from the referenced & other Discussions topics, none are not recognized as what is sometimes referred to as "standard folders" ... which I take to mean a set of mailbox names Mail knows to use for a particular purpose.
So, here is question #1: is this right? Does Mail come with a set of names it expects IMAP servers to use for sent mail, deleted mail (a.k.a Trash), junk mail, etc? Alternately, is there a standard for such things, or does Apple (for example) just include the .Mac mailbox names & expect the user to make any changes for other IMAP conventions?
I'm aware of the "Use This Mailbox For" function in Mail. However, this appears to be a one shot, one way deal: once you select one of the use options for a mailbox in an account, you cannot undo the choice. (IOW, there is no "none" choice.)
This leads to question #2: Is here a simple way to undo this?
AOL, possibly among others, has its own way of handling things like Spam & deleted items, so there isn't necessarily a direct correspondence with Mail's Junk & Trash mailboxes. Thus, I have no idea if Mail's 'use for' function would cause any problems if applied to them.
Question #3: Does anyone have any insights regarding this?
I would like to have a Mail trash mailbox that corresponds to AOL's version (which is a sort of grace period holding tank similar to Trash, except that AOL controls how long items stay in it before deletion from its servers). problem is, there is nothing like that that appears in Mail, either under the group account or elsewhere.
Question #4: Is there any way to create such a folder, or should one have been created in Mail's main Trash mailbox for this account by the app itself?
I just recently used the 'use for' function to tell Mail to use the AOL "Sent Items" originally in the AOL group account for mail sent from that account. This resulted in the mailbox being moved into Mail's main "Sent" mailbox & renamed "AOL IMAP." So far, so good, but leads to
Question #5: Is this what is supposed to happen?

Answer 1

(There was no indication of a need for, nor have
I entered, anything in the IMAP Path Prefix field.)
This is correct. You don't need anything to be put there.
This created an "AOL IMAP" inbox (in the inbox parent)
& an "AOL IMAP" account group mailbox with (@) icon,
This is expected behavior.
It is my understanding that the four subfolders
already exist on AOL's servers for any AOL subscriber.
That's probably the case. Mail certainly didn't create them by itself.
All four of these subfolders are supported by Mail.app.
Not sure what you mean here.
However, since all are created as subfolders in the 'group
account' I gather from the referenced & other Discussions
topics, none are not recognized as what is sometimes referred
to as "standard folders" ... which I take to mean a set of
mailbox names Mail knows to use for a particular purpose.
Correct. The fact that they appear in the account group means Mail isn't using them for any predefined meaning. And the reason is that they don't have the same name that Mail uses for them by default.
So, here is question #1: is this right?
Yes.
Does Mail come with a set of names it expects IMAP servers to use
I don't think Mail expects anything. It just creates the folders it uses by default if they aren't already there, and ignores the rest.
is there a standard for such things,
There is no standard, each server can do whatever it wants.
or does Apple (for example) just include the .Mac mailbox names &
expect the user to make any changes for other IMAP conventions?
Yes. And these names predate .Mac, actually. The same names are used by the *.mbox folders within any POP account folder in ~/Library/Mail/.
I'm aware of the "Use This Mailbox For" function in
Mail. However, this appears to be a one shot, one way
deal: once you select one of the use options for a
mailbox in an account, you cannot undo the choice.
(IOW, there is no "none" choice.)
This leads to question #2: Is here a simple way to undo this?
There has always to be a mailbox for each purpose (even if it has not been created yet), either stored locally or on the server. You cannot de-assign a folder for a standard behavior without telling Mail which other folder should be used instead -- by doing Use This Mailbox For on another mailbox or by telling Mail to not store those messages on the server, for example.
AOL, possibly among others, has its own way of handling
things like Spam & deleted items, so there isn't
necessarily a direct correspondence with Mail's Junk &
Trash mailboxes. Thus, I have no idea if Mail's 'use for'
function would cause any problems if applied to them.
Neither do I. Try it.
Question #3: Does anyone have any insights regarding this?
I don't know much about AOL myself. According to this article:
http://members.aol.com/adamkb/aol/mailfaq/imap/applemail.html
it seems that you must uncheck the Store messages on the server options (except for Trash), in order to be able to use AOL with Mail, but the problem could very well be just that AOL doesn't allow Mail to create new folders on the server, yet you can still tell Mail to use the ones created by AOL.
I would like to have a Mail trash mailbox that
corresponds to AOL's version (which is a sort of
grace period holding tank similar to Trash, except
that AOL controls how long items stay in it before
deletion from its servers). problem is, there is
nothing like that that appears in Mail, either under
the group account or elsewhere.
I have the feeling that Mail is already doing what you want, and the reason you cannot see that folder is because the name used by AOL is the same as the one used for Mail (Deleted Messages), and thus, Mail has already been using that folder for that purpose since the beginning.
Question #4: Is there any way to create such a
folder, or should one have been created in Mail's
main Trash mailbox for this account by the app itself?
In the Finder, go to ~/Library/Mail/IMAP-AOLaccount/. Do you see a Deleted Messages.imapmbox folder there? If yes, and that folder does not appear in the account group in Mail, then Mail is already doing what you want.
I just recently used the 'use for' function to tell
Mail to use the AOL "Sent Items" originally in the
AOL group account for mail sent from that account. This
resulted in the mailbox being moved into Mail's main "Sent"
mailbox & renamed "AOL IMAP." So far, so good, but leads to
Question #5: Is this what is supposed to happen?
Yes.
Regarding my #5 issue, I just noticed a new local
folder in Mail I assume was a result of choosing to
use "Sent Items" in the AOL IMAP account mailbox.
This mailbox is named (not surprisingly) "Sent
Messages (AOL IMAP)" & exists at the root mailbox level.
This is the folder Mail was using to store sent messages locally instead of on the server (when Preferences > Accounts > Mailbox Behaviors > Store sent messages on the server was not checked).
Problem is, the local "Sent Messages (AOL IMAP)"
mailbox doesn't contain any messages I sent from the
AOL account after I set Mail to use the "Sent Items"
mailbox for mail sent from that account.
Nor should it. You've told Mail to use another mailbox for that.
So, question #6 becomes: how do I get this local mailbox
to save a copy of messages I send from the account?
You don't. Mail will use it again (and it will disappear from the mailboxes list) if you disable Store sent messages on the server.
More weirdness: in Finder the info for this folder
says it was created at the same time as a "Drafts
(AOL IMAP).mbox" & shortly before creating "Junk (AOL
IMAP).mbox" ... yet these creation dates are
approximately one year before the main
"[email protected]" or its contents like
"Sent Items.imapmbox" were created! IOW, Finder tells
me these folders were created on my Mac around a year
before I set Mail up for the AOL account!
I have no idea what's going on here.