diff --git a/server-guide/jmap-server-guide.mdown b/server-guide/jmap-server-guide.mdown
index 2a10df2e..a84655df 100644
--- a/server-guide/jmap-server-guide.mdown
+++ b/server-guide/jmap-server-guide.mdown
@@ -1,3 +1,5 @@
+**Warning: this guide is outdated, it is based on an older draft of the JMAP specification**
+
 # Advice for JMAP implementors
 
 This document describes a recommended set of database tables and algorithms for efficiently implementing JMAP. It is intended to serve as suggestions only; there may well be better ways to do it. The spec is the authoritative guide on what constitutes a conformant JMAP implementation.