Threading with IMAP folders

[Matt Harrison <iwasinnamuknow@xxxxxxxxxxxxx>]

Hi all,

I used to be a long time religious user of mutt, but then i moved away to
firefox. Well now I'm back and trying to brush up my now rusty knowledge
of the best MUA on the planet.

I'm connected to an IMAP server with my spoolfile and folder set to the imap
server appropriately.

I've still got the old .muttrc I used to use and it had folder-hook's to set
the sort mode based on the folder. For example every folder except the inbox
and a few others were sorted by thread.

Now however, I can't get it to sort my imap mailboxes. I can do it manually
with "set sort=threads" but I can't get it to work automatically.

What is the accepted way to set the sort mode for imap folders?

Thanks in advance

Matt