add sieve

docs/index.md

@@ -46,3 +46,10 @@ POP3 is not supported.
 * Port: `587`
 * Encryption: `STARTTLS`
 * Username: Your LDAP user name
+
+### Sieve
+
+* Server: `mail.cccv.de`
+* Port: `4190`
+* Username: Your LDAP user name
+* Path seperator: `/` (example path: `INBOX/foobar`)