Many sites (with and without ssl) on 1 ip in ispmanager 5 how bad is it?

Question

ISPmanager

There is a VPS with ISPmanager 5 lite
ip address 1 pc. There are about 40 sites in the panel
(some with ssl
certificates ) index.html ) when checking in the column Valid Host Names and the like is the address of my other site. At the same time, everything seems to be working normally (sites are loaded without problems). I also discovered (using the https://www.mail-tester.com service ) that when sending EMail from the site, another (already 3rd) site (also mine) is displayed in the service headers.
It feels like 1 config is configured, which applies to all domains, and among them there is a dominant one, which for some reason pops up everywhere.
How critical is this in general and for PS in particular? Are we solving?

Answer 1

Are we solving?

Solvable. Contact the experts. They won't say anything without a diagnosis.
ps Clean up hostname, PTR and priority domain. To start.

Answer 2

Does not affect search results if you do not refer to
yourself