When I open a fresh installation of Kmail2 and I create a new maildir resource its name is "akonadi_maildir_resource_0". When I create the second one its name is "akonadi_maildir_resource_1" and so on...

If I delete this 2 accounts and try to create a new maildir resource its name is "akonadi_maildir_resource_2" even if I have no "akonadi_maildir_resource_0" and "akonadi_maildir_resource_1" configured.
In this situation I expect to see again a new "akonadi_maildir_resource_0" resource and not one named "akonadi_maildir_resource_2".

I have this behavior with all the resources and even if a click on "Add..." -> "Custom account" -> Maildir/Mbox/POP3/... ->  "OK" and then immediately on "Cancel" the ID of the resources grows continuously.
I tried also to run "akonadictl vacuum" and "akonadictl fsck" but I'm not able to restart my configuration from the ID "0". This is annoying. All the resources used in the past seems to be inside ".local/share/akonadi/db_data/ibdata1" DB even if they are been cancelled from the configuration.

This behavior has been implemented because into akonadi DB you can't reuse an old resource's ID already allocated in the past. It is right?
I could understand that, but for the end user this behavior could be associated with a bug in akonadi or with a problem in the GUI or with a not good/clean implementation.

I think that for the end user would be better see a random ID or simply "akonadi_maildir_resource" keeping the ID information under the hood. Have 4 POP3 resource named "akonadi_pop3_resource_1", "akonadi_pop3_resource_17", "akonadi_pop3_resource_23" and "akonadi_pop3_resource_31" only because he made some tests during the configuration of his accounts, is not good to see...

This is my opinion, obviously, but I hope that this behavior will change in the near future.

Thanks for your great work in akonadi. ;-)