[exim] exclude directory from quota

Hej,

I'm having a problem here with exims quota calculation. We're using

| maildir_tag = ,S=$message_size
| quota_size_regex = ,S=(\d+)

in exim.conf, and it's working great, with one exception. Courier IMAP
is generating Files in its "courierimapkeywords" folder, that are named
(not exactly, but close enough) like message files, but have zero size.
Now exim is calculating wrong mailbox sizes.

Is there a possibility to exclude specific directories from the quota?
I've seen there's an option maildir_quota_directory_regex in exim 4.40,
but that only works with maildirsize files. AFAICS there's no option to
exclude directories generally. Is it somehow possible to trick exim into
omitting these "courierimapkeywords" folders?


Thanks for any hints,
daniel