'All Mail' includes 'Spam'

Oh, sorry, then it's part of my problem I can't assign 'Mailbox Types' such as 'Junk' and 'Archive' to folders.

I forgot to mention it yesterday.
I tried to assign e.g. 'Archive' to 'All Mail'.

It still doesn't work here, on folders on different levels and different accounts.
It does work for some 'Draft' and Sent messages' folders. But I can't tell who assigned them, could have been MailMate.

'assigned': I meant 'created'. At the moment, I've got two 'Draft' folders, one in [Gmail], one in [Google Mail].

By default, MailMate does not handle the [Google Mail] prefix well. The
[Gmail] style is assumed and so is English mailbox names. It would of course be nice if this was improved.

One of your draft mailboxes may have been created by MailMate. It is
easier to see which one is correct and delete the wrong one in Gmails
web interface. (And you cannot delete IMAP mailboxes within MailMate
yet.)

But you should be able to assign all mailbox types manually. How does it
fail to assign, e.g., the Junk mailbox type to Gmails spam mailbox
(which is probably [Google Mail]/Spam in your case)? Could you elaborate.

A. Yeah, the folders confusion is definitely an issue between Google and me. It's best to check which labels to delete

B. Mailbox types:

1. I select some folder.
   
2. right-click or the "wheel thingie down there".
   
3. Select 'Mailbox type'

... Mmh, just solved some % of the riddle:

[['Draft' folders in [Gmail] are recognized, but I can't select]] No: 'Draft', 'Sent', 'Deleted' do work, but I can only select one if the last one is de-selected. Makes sense, one 'Draft' etc. per account.

It seems I can't select any folder as 'Junk' or 'Archive'. Regardless of position in the hierarchy.

Yes, there can only be 1 Draft mailbox for an account, but you should be
able to select the draft mailbox type for any mailbox (and it will then
automatically be deselected for any existing draft mailbox). I'll try to
see if I can find any problems with the relevant code, but if you have
any additional information it would be welcome.