diff --git a/Home.md b/Home.md
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@@ -7,3 +7,4 @@ GPG Lacre (Portuguese for a 'wax seal') is a content filter for Postfix that aut
 # Links
 * [Ideas](Ideas) for improvements.
 * Postfix documentation: [After-Queue Content Filter](http://www.postfix.org/FILTER_README.html).
+* [S/MIME Example Keys and Certificates](https://www.ietf.org/id/draft-ietf-lamps-samples-04.html), useful for testing.