diff --git a/HowtoOpenSMTPD.md b/HowtoOpenSMTPD.md
index 4654e700..0fc30935 100644
--- a/HowtoOpenSMTPD.md
+++ b/HowtoOpenSMTPD.md
@@ -1,5 +1,5 @@
 ---
-categories: OpenBSD, mail
+categories: OpenBSD email
 title: Howto OpenSMTPD
 ...