diff --git a/images/demo/Containerfile b/images/demo/Dockerfile
similarity index 100%
rename from images/demo/Containerfile
rename to images/demo/Dockerfile
diff --git a/images/dovecot/Containerfile b/images/dovecot/Dockerfile
similarity index 100%
rename from images/dovecot/Containerfile
rename to images/dovecot/Dockerfile
diff --git a/images/postfix/Containerfile b/images/postfix/Dockerfile
similarity index 100%
rename from images/postfix/Containerfile
rename to images/postfix/Dockerfile