[Dovecot] What's behind the message ...

[Frank Elsner]

... Warning: /media/Backup28a is no longer mounted. If this is intentional, remove it with doveadm mount

Hello,
        the above message appeared when I restarted dovecot.

What has dovecot to deal with my USB-Backup-Disk?
Dovecot cares about filesystem without any relation to the mail system?

Why this? What's bedind? 


Thanks in advance,
Frank Elsner