hello, recently installed a multi server system (ISPConfig3/Apache/Postfix/Dovecot/Roundcube) on wheezy with each server (web/db/mail) on a dedicated VM and dedicated iP. mulit-server setup includes one web, mail and db server. after set-up services like ISPConfig 3, phpmyadmin, roundcube etc. accessible and so far working fine, only that email sending & receiving doesn't seem to work. 2 questions related to this where i didn't find an answer to: 1.) Accidentally installed postfix, dovecot on the master server (i.e. the server where ISPConfig main & roundcube is installed/hosted, in my set-up i called it 'web'). is it ok to remove postfix/dovecot dependencies from this server or does the multi server environment need these packages on the master/host? 2.) debugging send/receive mail. As mentioned sending/receiveing mails is not working. Roundcube displays 'mail send successfully' but mail recipient never gets the mail. On the other direction - mails to be be received are never displayed in roundcube, and mail sender doesn't get an error returned either. Also mails that are sent from internally are not received. In etc/postfix/main.cf of the mail server the hostname = FQDN for my tld (mail.example.tld). What can i do to debug, any issues with the DNS or rather some settings in postfix or ISPConfig to be changed? thx in advance, all hints welcome.