Merge branch 'sieve_redirect_copy' into 'develop'

Sieve redirect needs :copy

See merge request ispconfig/ispconfig3!1220

server/conf/sieve_filter.master

@@ -17,7 +17,7 @@ if anyof (header :contains "X-Spam-Flag" "YES", header :contains "X-Spam" "Yes",
 <tmpl_if name="cc">
 # Send a copy of email to
 <tmpl_loop name="ccloop">
-redirect "<tmpl_var name='address'>";
+redirect :copy "<tmpl_var name='address'>";
 </tmpl_loop>
 </tmpl_if>