You can manually start a filesystem clean from the CLI:

1. Log into the CLI using SSH (or via serial) using an account with admin privileges.
2. To check how much space you will gain by running the clean, type:

   filesys show space

   The column Cleanable GiB will show the amount of storage that will be cleaned.
3. Start the filesystem clean by typing:

   filesys clean start

4. To monitor the process, type:

   filesys clean watch

   The monitor will run continuously in the CLI. Use Control + C to return to the prompt.

In a Mailman + ISPConfig type of setup, you may get the following error while sending an e-mail to the mailing list:

Error:

550 5.1.1 <leden@zweefvliegen-hasselt.be>: Recipient address rejected: User unknown in virtual mailbox table

When looking at the virtual aliases (in /var/lib/mailman/data/), the lists are empty.

You can resolve this by regenerating the aliases:

sudo /var/lib/mailman/bin/genaliases
sudo postmap /var/lib/mailman/data/transport-mailman
sudo postmap /var/lib/mailman/data/virtual-mailman

Afterwards, restart Postfix:

sudo service postfix restart