[Exim] Hmm

Out of curiosity...

I am using mysql for my lookups, and I have the following code for
local_domains:

domainlist local_domains = \
~  ${lookup mysql {SELECT domain FROM domains \
~    WHERE type="local" and domain="${domain}" }}

My question is this:

What effect does "and domain="${domain}" have on the results of that
query. What value does ${domain} expand to?

ahp