Hello, I am not an expert in ispconfig and I need your help. I have installed a server following the instructions ispconfig 3.1 (Ubuntu 18.04.3 LTS (Bionic Beaver)), I cannot use the SMTP mail service because my IP does not have PTR registration and all emails end in Spam. So I use my domain with the Yandex.com mail service. but the problem is that I don't know how to integrate this external mail server to ispconfig to be able to send emails from php mail in my domain. I was reading in the forum and followed the instructions to add the MX record mx.yandex.com but the emails still leave the local SMTP server of ispconfig and end in spam. The DNS records are not in ispconfig, they are in cloudns.com and there I have the MX record mx.yandex.com so that the mail service of yandex.com can work. try to create a DNS zone for the domain in ispconfig and add the same MX record mx.yandex.com but the mail still goes out from the local SMTP server. I don't know if I'm doing it wrong. please help!