diff --git a/core/start-service.sh b/core/start-service.sh
index d8045d1..b216802 100755
--- a/core/start-service.sh
+++ b/core/start-service.sh
@@ -14,6 +14,8 @@ KCCONF_MONITOR_SERVER_SOCKET=${KCCONF_MONITOR_SERVER_SOCKET:-"file:///var/run/ko
 KCCONF_SEARCH_SERVER_SOCKET=${KCCONF_SEARCH_SERVER_SOCKET:-"file:///var/run/kopano/server.sock"}
 KCCONF_SPOOLER_SERVER_SOCKET=${KCCONF_SPOOLER_SERVER_SOCKET:-"file:///var/run/kopano/server.sock"}
 KOPANO_CON=${KOPANO_CON:-"file:///var/run/kopano/server.sock"}
+KCCONF_SPOOLER_SMTP_SERVER=${KCCONF_SPOOLER_SMTP_SERVER:-mail}
+KCCONF_SPOOLER_SMTP_PORT=${KCCONF_SPOOLER_SMTP_PORT:-25}
 
 # copy configuration files to /tmp/kopano to prevent modification of mounted config files
 mkdir -p /tmp/kopano
@@ -247,7 +249,7 @@ search)
 spooler)
 	dockerize \
 		-wait "$KOPANO_CON" \
-		-wait tcp://"$KCCONF_SPOOLER_SMTP_SERVER":25 \
+		-wait tcp://"$KCCONF_SPOOLER_SMTP_SERVER":"$KCCONF_SPOOLER_SMTP_PORT" \
 		-timeout 1080s
 	# cleaning up env variables
 	unset "${!KCCONF_@}"
diff --git a/docker-compose.yml b/docker-compose.yml
index 86f6aa5..cd64316 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -305,6 +305,7 @@ services:
     environment:
       - KCCONF_SPOOLER_LOG_LEVEL=3
       - KCCONF_SPOOLER_SMTP_SERVER=mail
+      - KCCONF_SPOOLER_SMTP_PORT=25
       - KCCONF_SPOOLER_SSLKEY_FILE=/kopano/ssl/kopano_spooler.pem
       - SERVICE_TO_START=spooler
       - TZ=${TZ}