When using RBLs to generate warning headers, what happens if the host
is listed at more than one RBL site? Does Exim generate a single
X-RBL-Warning header with the text from the first match and then stop;
or does it check them all and generate multiple headers?
I suspect it does the former (stop on first match); but I think it would
be useful to be able to request the later. (For warnings only. There
isn't much point in continuing the checks if the message will be rejected.)
