[RCU] newbie

New to roundcube and dovecot - bear with me if this questions are too basic.

On Debian I got dovecot working for imap and pop3. Installed them with apt-get install ...

Postfix has been running for a while.

I configured dovecot to access the incoming mail from the correct location. Testet receiving mail with my mail client using pop. Stopped the mail client from periodically receiving mail.

How can I see new incoming mail in roundcube Inbox? I checked that postfix has written new mail at the inbox location but dovecot does not update their indexes.

Something simple is missing here I guess.