Update u_e-dovecot-vmail-volume.md

docs/u_e-dovecot-vmail-volume.md

@@ -1,3 +1,20 @@
+## The "new" way
+
+**WARNING**: Newer Docker versions seem to complain about existing volumes. You can fix this temporarily by removing the existing volume and start mailcow with the override file. But it seems to be problematic after a reboot (needs to be confirmed).
+
+An easy, dirty, yet stable workaround is to stop mailcow (`docker-compose down`), remove `/var/lib/docker/volumes/mailcowdockerized_vmail-vol-1/_data` and create a new link to your remote filesystem location, for example:
+
+```
+mv /var/lib/docker/volumes/mailcowdockerized_vmail-vol-1/_data /var/lib/docker/volumes/mailcowdockerized_vmail-vol-1/_data_backup
+ln -s /mnt/volume-xy/vmail_data /var/lib/docker/volumes/mailcowdockerized_vmail-vol-1/_data
+```
+
+Start mailcow afterwards.
+
+---
+
+## The "old" way
+
 If you want to use another folder for the vmail-volume, you can create a `docker-compose.override.yml` file and add the following content:
 
 ```