Mail keeps creating inboxes

Question

I use Apple Mail on both my MacBook and iPhone to sync with my IMAP account and have recently acquired a problem:
Although I don't use the To Do function in Mail, Mail has been creating an Apple Mail To Do folder in my iPhone/MacBook folder list. At first this was at the top level of the hierarchy, same as my other mail folders. I deleted it when first noticed and have attempted to delete again since (perhaps foolishly), and now Mail keeps creating new copies of the "Apple Mail To Do" folder, only… each time it is nested inside two, three, four, five(!) "Inbox" folders.
Looks like this:
- INBOX
- ....INBOX
- ........INBOX
- ............INBOX
- ................INBOX
- .....................Apple Mail To Do
This set of folders sits in alpha order within my main list of folders, it's separate from the real Inbox that sits at the top of my folder list.
When I attempt to delete all six folders I get a message saying that the various INBOXES don't exist. When I delete just the To Do folder, the INBOX folders are deleted as well. (Until the whole thing is recreated!)
Incidentally, my IMAP Path Prefix in Mail.app's preferences is set to: INBOX
So I suspect if I were to change that to blank, then the nesting would (maybe?) stop.
All the same, can anyone explain this behaviour (it's fairly recent, following a decent period where I wasn't plagued by To Do folders at all)? Why would it be nesting multiple "INBOX" folders, rather than just one?
What can I do to get the To Do folder to stay away?

Answer 1

This solution does not delete the AppleMail Todo mailbox but provides a workaround that keeps those annoying subfolders out of your inbox and prevents them from "breeding."
(Note: In my case this issue began only after I started using an iPhone. I am using a 3rd party IMAP server provided by Network Solutions WITHOUT SSL. I cannot say the following is a universal workaround.)
The wage-donkey I spoke to at Apple Tech support- "Tier 2" no less - INSISTED this is not a problem caused by mail.app, but rather it was a server-side issue. He said the folder in question MUST exist on the server and is being pushed to the mac every time the IMAP mailbox is created in mail app. Rather than attempting to trouble-shoot the issue, he adamantly argued his point until I hung up.
You can attempt to prove his point for him by trying the following:
1) Log on your mail server via web browser and delete the offending folders.
2) move ~/Library/Mail and ~/Library/Preferences/apple.mail.plist to the trash.
3) Disconnect computer from the internet.
4) Set-up IMAP account manually.
5) Relaunch mail.app.
The application will request permission to create an Apple Mail ToDo folder in the newly created Inbox.
(It would seem Mail.app is designed to automatically create the ToDo mailbox and place it on the server, which it cannot do without an internet connection. One would assume a "Tier 2" Apple Support technician would know this. He didn't.)
6) Hit cancel to deny Mail.app's request.
The server-side folders that should normally appear in a mailbox OUTSIDE of your inbox should now all be contained WITHIN the mailbox. This should include a Gray folder called "ToDo" with a subfolder mbox (youraccountname)
7) Quit mail.app
8) Restore your internet connection.
9) Relaunch mail.app. It will make the same request as step 5. Click ALLOW.
Mail.app should move all of the folders from your inbox to a server-side subfolder containing the Gray ToDo folder and the subfolder "mbox (youraccountname)."
DO NOT delete this folder. You can open it without consequence. You should no longer have the issue of subfolders breeding in your inbox every time you reboot.
To further test the mai.app-side/server-side argument, I deleted the entire mailbox from the server and created a new one before trying the above steps. Same issue. The folder in question is almost certainly created by mail.app and not residing on the server. Though I cannot isolate the cause, I'm confident it lies somewhere in the combination of SSL settings, iPhone integration and mail.app.
In my experience, Mac Tech Support has not helped solve a real problem since OS 9. In one instance a mac "genius" suggested my mother wipe her drive and reinstall the OS to solve her airport problem. It turns out all he had to do was turn off Interference Robustness in her airport settings. User message boards know more collectively than any Tech Support Associate I have ever encountered. Apple doesn't want to take your call so take the hint and stop calling.