[exim] Includecontent not updated

Exim version 4.92.3 #3 built 30-Sep-2019 11:25:19

Hi,

Exim has this entry in it's main.conf:

.include_if_exists /etc/exim/forwarder_dl.conf

it contains a domainlist :

domainlist local_domains = @ : localhost : localhost.localdomain : <SQL
QUERY >

Is there any particular reason, why the content of domainlist is only
loaded once after server restart and not on every email handled,
as it should?

best regards,
Marius