Updated Configuring Sieve filters (markdown)

docs/content/advanced/mail-sieve.md

@@ -30,3 +30,24 @@ redirect :copy "user2@otherdomain.tld";
 ```
 
 For more examples or a detailed description of the Sieve language have a look at [the official site](http://sieve.info/examplescripts). Other resources are available on the internet where you can find several [examples](https://support.tigertech.net/sieve#sieve-example-rules-jmp).
+
+### Manage Sieve
+
+The [Manage Sieve](http://wiki1.dovecot.org/ManageSieve) extension allows users to modify their Sieve script by themselves. The authentication mechanisms are the same as for the main dovecot service. ManageSieve runs on port `4190` and needs to be enabled using the `ENABLE_MANAGESIEVE=1` environment variable.
+
+```
+(docker-compose.yml)
+ports:
+ - ...
+ - "4190:4190"
+environment:
+ - ...
+ - ENABLE_MANAGESIEVE=1
+```
+
+All user defined sieve scripts that are managed by ManageSieve are stored in the user's home folder in `/var/mail/domain.com/user1/sieve`. Just one sieve script might be active for a user and is sym-linked to `/var/mail/domain.com/user1/.dovecot.sieve` automatically.
+
+***Note:*** ManageSieve makes sure to not overwrite an existing `.dovecot.sieve` file. If a user activates a new sieve script the old one is backuped and moved to the `sieve` folder.
+
+The extension is known to work with the following ManageSieve clients:
+ * Thunderbird with latest **Sieve** extension. If the extension doesn't work with the add-on available directly from within Thunderbird, try the developer build at https://github.com/thsmi/sieve.