Q:

Move E-Mails to subfolder of inbox using sieve

Do I need any option, to move matching emails to a subfolder of the inbox? 
My /etc/dovecot/conf.d/10-mail.conf:
    namespace inbox {
      inbox = yes
    }

And the /srv/vmail/spam-global.sieve:
    if address "From" "monitoring@example.com" {
            fileinto "INBOX.Monitoring";
    }

This configuration is currently creating a new main folder "INBOX.Monitoring" instead of an INBOX subfolder "Monitoring". 

A:

Use / as parent-child separator: "INBOX/Monitoring"

