diff --git a/package_versions.sh b/package_versions.sh
new file mode 100755
index 0000000..4ec1d8c
--- /dev/null
+++ b/package_versions.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+#
+# List versions of relevant packages in mailserver container.
+#
+
+set -euo pipefail
+
+container="${1:-ghcr.io/t-lo/mailserver:latest}"
+packages_file="${2:-release_package_versions.list}"
+
+while read -u 9 line; do
+    name="${line%,*}"
+    cmd="${line#*,}"
+    echo -n "* ${name}: "
+    docker run --entrypoint /bin/bash --rm -i "${container}" -l -c "${cmd}"
+done 9<"${packages_file}"
+
+echo -n "* Postfix prometheus exporter: "
+sed -n 's/.*postfix_exporter_version=//p' Dockerfile
+
+echo -n "* Fail2Ban prometheus exporter: "
+sed -n 's/.*fail2ban_exporter_version=//p' Dockerfile
diff --git a/release.sh b/release.sh
index 2f37621..0eaa318 100755
--- a/release.sh
+++ b/release.sh
@@ -51,20 +51,7 @@ docker build --pull -t "${container}:${version}" .
 docker tag "${container}:${version}" "${container}:latest"
 
 yell "Querying version information"
-{
-    while read -u 9 line; do
-        name="${line%,*}"
-        cmd="${line#*,}"
-        echo -n "* ${name}: "
-        docker run --entrypoint /bin/bash --rm -i "${container}:${version}" -l -c "${cmd}"
-    done 9<release_package_versions.list
-
-    echo -n "* Postfix prometheus exporter: "
-    sed -n 's/.*postfix_exporter_version=//p' Dockerfile
-
-    echo -n "* Fail2Ban prometheus exporter: "
-    sed -n 's/.*fail2ban_exporter_version=//p' Dockerfile
-} > PACKAGE_VERSIONS
+./package_versions.sh "${container}:${version}" release_package_versions.list | tee PACKAGE_VERSIONS
 
 yell "Creating the release tarball"
 echo "${version}" >VERSION