[exim] prefer IPv6 over v4?

Hey everyone, quick question, more an idle thought. When exim looks up a
mail to be delivered via remote_smtp, it seems to always prefer to use
IPv4 even when a v6 address is available. For example, in my log I see a
message delivered to a gmail address. But both Source and Destination
IPs are ipv4 format, even though dig aaaa gmail-smtp-in.l.google.com
shows a ipv6 address. Is there some option somewhere that can be set
that will tell exim to deliver to IPv6 addresses unless no such address
is available, and then fall back to IPv4?

Thanks!

--
Dan Egl
From my Test Server