Hello All, I desperately need now some help after trying endless possibilities. I do have my domains registered at GoDaddy, so I've been keeping them always separate from my host. I have now started with a dedicated server. All is working perfectly fine except the emails. I simply can't get that work, neither on Outlook 2013, nor webmail. Webmail is opening fine but when trying to send, I get an error message "authentication required. Must issue STARTTLS command first" On Outlook 2013 I am able to send, but not receive. Any testmail that I am trying to send to my dedicated server get's immediately rejected. SMTP error from remote server after RCPT command: host: 5.7.1 Client host rejected: Access denied However, I believe that might be also somehow related to my main problem, which are the DNS settings. Which are the correct settings at GoDaddy (screenshot attached) Also attached, ISPConfig 3 registered DNS. When entering the details of ISPConfig at Godaddy, it simply won't work. Server: (Debian Jessie) ISPConfig 188.8.131.52p8 Using Dovecot Much obliged for any hint on how to set it up correctly.