Message moved to Spam folder mysteriously

[Alfredo Saldanha]

Hi there,

How dovecot move the message to Spam without antispam plugin installed or sieve rule to move to this folder?
I have no configuration to do this.

My logs:
Sep 10 12:12:44 mda02 dovecot: imap(my.user at mydomain.com): Warning: Inotify instance limit for user 5000 (UID vmail) exceeded, disabling. Increase /proc/sys/fs/inotify/max_user_instances
Sep 10 12:12:45 mda02 dovecot: imap(my.user at mydomain.com): copy from INBOX: box=Spam, uid=134, msgid=<466c888b2179f7e2c0fc74b186396785 at mydomain.com>, size=2838
Sep 10 12:12:45 mda02 dovecot: imap(my.user at mydomain.com): expunge: box=INBOX, uid=826, msgid=<466c888b2179f7e2c0fc74b186396785 at mydomain.com>, size=2838

I don't have any client connected at the imap server in this time.

Some tip?

BR,

Alfredo