JSIEVE-67 Update RFC references
diff --git a/src/site/xdoc/index.xml b/src/site/xdoc/index.xml
index 6e598d2..f42f336 100644
--- a/src/site/xdoc/index.xml
+++ b/src/site/xdoc/index.xml
@@ -29,7 +29,7 @@
<p>
jSieve is a Java implementation of the Sieve mail filtering
language defined by
- <a href='http://www.rfc-editor.org/rfc/rfc3028.txt'>RFC 3028</a>
+ <a href='https://tools.ietf.org/html/rfc5228'>RFC 5228</a>
. jSieve is implemented as a language processor that can be
plugged into any internet mail application to add Sieve support.
</p>
