I've an ispconfig 3.1 multiserver setup with 2 mail and 2 web servers. The outlook.com has banned our isp's ip addresses due to spam activity. I'd like to use a third mail relay server to sending mail from our domains. Is there any "ispconfig friendly solution" for this problem? (Setup the relaying for all existing domains, setup new dkim records, and new (dkim)dns entries? Expedient to join the new mail server to the existing ispconfig multiserver configuration? Thanks!