I'm getting the same error note for a GMail account:

Select failed, server replied: A000266 NO Unknown Mailbox: ( now in authenticated state ) ( Failure ) [ Gmail  ]

I don't have any errors of the latter kind.

I started with a fresh configuration (so no migration) and I am getting messages like this as well:
Select failed, server replied: A000057 NO Unknown Mailbox: ( now in authenticated state ) ( Failure ) [ Gmail  ]
Select failed, server replied: A000141 NO Unknown Mailbox: ( now in authenticated state ) ( Failure ) [ Gmail  ]
Select failed, server replied: A000157 NO Unknown Mailbox: ( now in authenticated state ) ( Failure ) [ Gmail  ]

They started appearing once I disabled Nepomuk (which I did because virtuoso-t was using 187% of my CPUs - I have dual cores)

Select failed, server replied: A000231 NO Unknown Mailbox: ( now in authenticated state ) ( Failure ) [ Gmail  ]

It looks like the number is growing ;)

Here to confirm this

Select failed, server replied: A000072 NO Unknown Mailbox: ( now in authenticated state ) ( Failure ) [ Gmail  ]

Really annoying when you come back to find you have run out of resources rendering the billion message boxes (it could happen). Then to click though them all.

Gahh! it just went off again.

Kubuntu 10.10 KDE 4.6Beta2

Once I started using KDEPIM4.6 from experimental PPA I get this error. KDE contacts toasted my calendar, but that another bug. This KDE PIM does not seem to be working out too well with Google.

with kubuntu 11.04 (kde 4.6 rc1 and kde pim 4.6 beta3), i have this error:

Select failed, server replied: A000175 NO Unknown Mailbox: ( now in authenticated state ) ( Failure ) [ Gmail  ]

*** This bug has been confirmed by popular vote. ***

same error with kde 4.6 rc2 and kdepim 4.6 beta 4

After last update in Kubuntu 10.10 with akonadi server 1.4.95-0ubuntu1~maverick1~ppa1 I don't get this error messages - so at least in Kubuntu it seems to be fixed :)

(In reply to comment #9)
> After last update in Kubuntu 10.10 with akonadi server
> 1.4.95-0ubuntu1~maverick1~ppa1 I don't get this error messages - so at least in
> Kubuntu it seems to be fixed :)

in natty, this issue isn't fixed!

(In reply to comment #10)
> (In reply to comment #9)
> > After last update in Kubuntu 10.10 with akonadi server
> > 1.4.95-0ubuntu1~maverick1~ppa1 I don't get this error messages - so at least in
> > Kubuntu it seems to be fixed :)
> 
> in natty, this issue isn't fixed!

Starting kde with empty session (no saved session), i don't have this error in kmail..maybe it's fixed!

Right now I am running KDE 4.5.95, KDE PIM 4.5.94 (in Arch, for some reason, it's in a different version), akonadi 1.4.95, Qt 4.7.1 and this problem doesn't happen anymore. I have nepomuk and strigi disabled.

Please have a look at https://mail.google.com/mail/?shva=1#settings/labels

Make sure that the folders for which you get errors are shown on imap (there's a checkbox)


For those who have this particular error :

> A000175 NO Unknown Mailbox: ( now in authenticated state ) ( Failure ) [ Gmail  ]

make sure the sent, archive, trash or spam folders are checked (one should be enough)

(In reply to comment #13)
> Please have a look at https://mail.google.com/mail/?shva=1#settings/labels
> 
> Make sure that the folders for which you get errors are shown on imap (there's
> a checkbox)
> 
> 
> For those who have this particular error :
> 
> > A000175 NO Unknown Mailbox: ( now in authenticated state ) ( Failure ) [ Gmail  ]
> 
> make sure the sent, archive, trash or spam folders are checked (one should be
> enough)

with kde 4.6.0 final and kdepim 4.5.94, i don't have this issue..it seems to be fixed.

I was able to workaround this by removing the [GMail] label from the local subscriptions. I suspect that the problem is caused by labels that exist in kmail but don't exist in gmail. Steps to reproduce:

1) create a lable named test/test2 in gmail (without creating the label test)
2) check mail in kmail
3) kmail will create a test dir and a test2 subdir
4) kmail will try to parse the test/  dir with no luck.

The same must be happening for the [GMail] dir. I hope that this helps

In KDE 4.6 installed from kde-redhat-testing repo in Fedora 14 x86_64 this bug still remains. Everything was fine until disabling Nepomuk bacause it consumed 100% of CPU. Then this messages began appeared. Nepomuk enabling didn't help.

When is label [Gmail] created in Google Mail everything is ok. Problem is in checking non-existent folder [Gmail]

*** Bug 270592 has been marked as a duplicate of this bug. ***

I just installed Kontact 4.5.95 under Kubuntu 11.04, and I also have this bug.

Creating the label '[Gmail]' in google mail also fixes my problem.

Fresh install of Kubuntu 11.04 and KMail Version 1.13.6 Using KDE Development Platform 4.6.2 I setup GMail with IMAP and get an error when retrieving mail:

Error while querying the server status. Unable to open folder [Gmail]. The server replied: [NONEXISTENT] Unknown Mailbox: [Gmail] (now in authenticated state) (Failure)

To fix the problem I removed the [Gmail] folder from synchronization:

1. Right-click on [Gmail] (error will popup if not already viewing folder)
2. Uncheck "Include this folder in mail checks"
3. OK

I ran into this bug only recently and it is very annoying indeed.
After some experimentation, I found a solution: 

1. Under "server-side subscriptions" tick all the folders you want, including the [Gmail] folder.

2. Under "local subscriptions" un-tick the [Gmail] folder. 

3. Restart Kontact/Kmail.

All folders show up without the annoying error message and the [Gmail] folder is greyed out (as it used to be, iirc).

Forgot: 

Kontact 4.6 beta5
KMail: 2.0.95
KDE 4.6.2
Qt: 4.7.2
on Kubuntu 11.04

Thank you Henning, your workaround (comment #22) solved it for me. 
Event though, I think this should work out of the box in kmail..so it should handle empty/nonexistent folders. 
Cheers, Mark

*** Bug 258403 has been marked as a duplicate of this bug. ***

I have this problem as well and can confirm that creating a [Gmail] label seems to be work around.  Would be nice if Kmail could handle this itself without the need to create a label in Gmail for it.

*** Bug 272854 has been marked as a duplicate of this bug. ***

*** Bug 275567 has been marked as a duplicate of this bug. ***

*** Bug 279924 has been marked as a duplicate of this bug. ***

After a few tests:

- The notification about "NO Unknown Mailbox: [any folder name]" only appears if akonaditray is running,

- The warning appears only on gmail accounts which internally doesn't use real folders but labels appearing as folders (either on their web interface or with imap),

- The warning appears for internal labels, eg: '[Gmail]','[Imap]' or if you have sub-labels with non-existing parent label.

Example, if you create a "foo/bar" label without first creating "foo" on GMail's web ui, you get a warning about "foo"

Imap supports two "modes" of directories. "Next to Inbox" and "Inside Inbox". My hosting provider uses "Inside Inbox" an I get a similar error. When looking at the log there are error like this

AgentBase(akonadi_imap_resource_0): Select failed, server replied: A016281 NO Unknown namespace. 
NotificationManager::notify ( Collection (68, .Launchpad) in collection 33 modified parts (timestamp) )

Should'nt the namespace be INBOX.Launchpad instead of .Launchpad?

Git commit c866112da748bfc2c357c80d1798a252c55854eb by Kevin Ottens.
Committed on 16/09/2011 at 22:31.
Pushed by ervin into branch 'master'.

We're not supposed to care about the casing, so lowercase the flags

CCBUG: 258635

M  +2    -0    kimap/listjob.cpp

http://commits.kde.org/kdepimlibs/c866112da748bfc2c357c80d1798a252c55854eb

Git commit d608bc432c8b373d829cfe113efea9e90fa0e41e by Kevin Ottens.
Committed on 16/09/2011 at 22:32.
Pushed by ervin into branch 'master'.

We now get the flags in lower case so adapt to that

BUG: 258635

M  +3    -3    resources/imap/retrievecollectionstask.cpp
M  +1    -1    resources/imap/subscriptiondialog.cpp

http://commits.kde.org/kdepim-runtime/d608bc432c8b373d829cfe113efea9e90fa0e41e

for me about "NO Unknown Mailbox: [any folder name]" notification, the best solution was create a [Gmail] label in web-interface of gmail and all was ok, because only delete in local-subscription all sub-folders of Gmail was not practical solution because sometimes gmail filter emails to Gmail>Spam and is not really a spam, and Gmail>Trash is easier to "empty" it.  Thanks for this around.

I tried creating the [gmail] label, but that didn't fix it.

Better still, Right clicking on the IMAP Config in kmail2, using "Local Subscriptions" and removing the Gmail folder stops the error message and improves the performance - not needing to syncronise all those extra folders too.

*** Bug 282986 has been marked as a duplicate of this bug. ***

Git commit 84edd007f903763b61296a84768e2f4c9f98113a by Andras Mantia, on behalf of Kevin Ottens.
Committed on 16/09/2011 at 22:31.
Pushed by amantia into branch 'KDE/4.7'.

We're not supposed to care about the casing, so lowercase the flags

CCBUG: 258635
(cherry picked from commit c866112da748bfc2c357c80d1798a252c55854eb)

M  +2    -0    kimap/listjob.cpp

http://commits.kde.org/kdepimlibs/84edd007f903763b61296a84768e2f4c9f98113a

Git commit dc60f1116dad12fbdd443a964d58eec7e5ed09fc by Andras Mantia, on behalf of Kevin Ottens.
Committed on 16/09/2011 at 22:32.
Pushed by amantia into branch 'KDE/4.7'.

We now get the flags in lower case so adapt to that

BUG: 258635
(cherry picked from commit d608bc432c8b373d829cfe113efea9e90fa0e41e)

M  +3    -3    resources/imap/retrievecollectionstask.cpp
M  +1    -1    resources/imap/subscriptiondialog.cpp

http://commits.kde.org/kdepim-runtime/dc60f1116dad12fbdd443a964d58eec7e5ed09fc

*** Bug 283316 has been marked as a duplicate of this bug. ***