value must be of the form User-Name:/regexpmatch/replacement/. Example usage:
<blockquote>
<para>
-rewriteAttribute User-Name:/^(.*)@local$/$1@example.com/
+rewriteAttribute User-Name:/^(.*)@local$/\1@example.com/
</para>
</blockquote>
</para>
replacement specifies how to replace the matching regexp. Example usage:
<blockquote>
<para>
-modifyAttribute 1:/^(.*)@local$/$1@example.com/
+modifyAttribute 1:/^(.*)@local$/\1@example.com/
</para>
</blockquote>
</para>