diff --git a/conf/postgrey_whitelist_clients b/conf/postgrey_whitelist_clients
index c2ad2c82..ee19722b 100644
--- a/conf/postgrey_whitelist_clients
+++ b/conf/postgrey_whitelist_clients
@@ -16,3 +16,4 @@
 /^o\d+\.outbound-mail\.sendgrid.net$/
 /^box.kroes.email$/
 /^.*.hes.trendmicro.eu$/
+/^smtp-\d+\.steampowered\.com$/