I have the problem with kmail 2 that i have no trash folder. I migrated from kmail1 to kmail2. I got nearly everything to work again (it wasn't easy), and now i'm left with that last task. I also have that repeated error:
"Local Folders: Maildir '' for collection '' is invalid."

I have a feeling that this might be connected. The Local folder configuration points to a valid folder (lets say existing). The only strange thing is, that that folder has no files (not even hidden ones), just 3 folders (again empty), new, cur and tmp.

I did not find a way to create a new trash folder. Any ideas?

I found out that there is a bugreport on this:
https://bugs.kde.org/show_bug.cgi?id=285532

Sadly no progress

So there is now way to repair a local kmail folder if the trash folder is missing? What is the proposed plan to solve this? Export all emails, delete all of kmail/akonadi configs and reimport them?

I got a new clue on this puzzle.
I disabled nepomuk, and now the trash folder is here. Should i use kontact without nepomuk?

You will not be able to perform any searches inside KDE PIM applications without Nepomuk unfortunately.

Interesting however, that disabling Nepomuk triggered the creation/appearance of the Trash folder. Does it disappear again if you re-enable Nepomuk?

Yes, it stayed when i switched it back on.
But i still have this error message everytime i retrieve emails (retrieving works, but something has to be wring):

"Local folders: Maildir '' for collection '' is invalid."

It appears that your Local Folders structure contains an invalid folder which is causing KMail issues. Unfortunately I do not know how to differentiate between valid and invalid folders at the file system level for KMail, so please send a mail to kdepim-users@kde.org regarding this so that others may be able to help as well.

Hi all,

I'm relatively new to kde (I use it on a regular basis since two months), so bear with me: I might have written something completely wrong.

As others, I had no trash folder in kmail, an annoying problem as the risk to delete an e-mail by accident is always here. After tweaking around with the maildir folder (I'm new to that too, as I was running thunderbird until recently –I switched to kmail to get a better integration), I was about to give up and go back to thunderbird when I inavertently and fortunaly stumbled on the solution. It can be found here under the paragraph

Local Folders is added over and over

Now, the solution needed a bit of reading and hadn't I seen that:

If you "lost" your Trash folder and want to set a new folder to act as Trash, you can use the same approach described above, but for the SpecialCollectionAttribute value enter trash .

I would have missed it.

Anyway, here's how I did it:
First, I open the akonadi console and under my Local folder, I put a new folder. I right click on this new folder and open "folder properties", go to the Attributes Tab, enter SpecialCollectionAttribute, then Add, once SpecialCollectionAttribute is in the list, I double click on the line under Value and enter trash. Now, you need to make the trash folder visible, to do that, you write ENTITYDISPLAY, add, then, in the value column, something like that ("trash" "user-trash" "" ()), click OK, restart the akonadi server and that's it, the trash folder is back! Now, moving a mail to the trash will result in it appearing here, from where you should be able to delete it, too.

Note that ("trash" "user-trash" "" ()) defines the appearance of the your folder, between the first quote marks is the name while the second and third refer to the icon (in that case, there is only one icon, user-trash, but you could add another one in case you move unread messages in there).

Hope this helps

Berneri wrote:Hi all,
[...]
First, I open the akonadi console and under my Local folder, I put a new folder. I right click on this new folder and open "folder properties", go to the Attributes Tab, enter SpecialCollectionAttribute, then Add, once SpecialCollectionAttribute is in the list, I double click on the line under Value and enter trash. Now, you need to make the trash folder visible, to do that, you write ENTITYDISPLAY, add, then, in the value column, something like that ("trash" "user-trash" "" ()), click OK, restart the akonadi server and that's it, the trash folder is back! Now, moving a mail to the trash will result in it appearing here, from where you should be able to delete it, too.

Note that ("trash" "user-trash" "" ()) defines the appearance of the your folder, between the first quote marks is the name while the second and third refer to the icon (in that case, there is only one icon, user-trash, but you could add another one in case you move unread messages in there).

Hope this helps

Berneri:
Thanks for pointing to this solution.
It was actually not that complicated and it solved a major issue for me.

I had the same issue and was just about to apply the resolution listed above. However last night I upgraded to KDE 4.9.4 (using KMail 4.9.4) and behold, my Trash was back, icon and all. I can only assume that there was a fix in the latest release.

With KDE 4.10.2 "release 1"
the steps following the instruction
http://userbase.kde.org/KMail/FAQs_Hints_and_Tips#Store_trash_mails_in_a_special_folder
were successful!