[exim] domainlist: Howto create sections?

Hi,

I'd like to express something like

    domain either in list1 or in list2 and list3

I can say

domainlist listX = +list1 : +list2

to create a union of the two lists. Since a section is the negative
of the union of the negatives, I tried

domainlist not2or3 = !+list2 : !+list3

But that won't work, as when negations enter the lists cannot be
considered anymore as union of the elements (e.g. all non-list2 domain
match the first and never check the second).

So how can I have domain list sections?

The background is that I'd like to model sendmails bestmx_is_local
feature with restricted scope, e.g.

# Accept mail as local if in local_domains or we are primary mx of the
# domains in +localmx_domains
domainlist localdelivery = +local_domains : Intersection( @mx_primary, +localmx_domains)

Thanks!
--
Axel.Thimm at ATrpms.net