Add the CNAME entries to your DNS configuration. I can't do it on ISPConfig. Please explain step by step how to do it.
AcyMailing Sending Service - trouble with configuration
mihhaSupport Beginner
You should check ISPConfig documentation or contact their support
https://docs.ispconfig.org/dns-basics/canonical-dns-records/
We can't provide support for 3rd party systems
Thank you for your understanding