How can I run fetchmail on a Zarafa server?

When you do not have a local MTA configured on the server with Zarafa installed, you need to run the Zarafa-dagent via Fetchmail. In fetchmail configuration file you should at the following option: mda "/usr/sbin/zarafa-dagent username"

See a full example fetchmail configuration below:

  poll 192.168.1.254
    localdomains zarafa.com
    protocol pop3
    no dns
    username john
    password 'password'
    to *
    smtpaddress zarafa.com
    fetchall
    forcecr
    set postmaster user
    mda "/usr/bin/zarafa-dagent john"

The fetchmail configuration should be made for every user individual.

See here for more information about Fetchmail.