[exim] TLS in recipient callouts

Hello

I was playing with recipient verification callouts and found that the
callout fails if the upstream server requires TLS.

I found a discussion thread on this from 2004 here:

http://www.gossamer-threads.com/lists/exim/users/30997

I can see nothing in the docs to suggest that this has been implemented.
Is that in fact the case?

Thanks

Martin.