Question Sending emails to bounced addresses

[spg_nueve]

Server operating system version

Centos 7.9

Plesk version and microupdate number

Plesk Obsidian 18.0.65, actualización 2 Web Host Edition

Hello, in sender score it says that my server is sending mail from the email addresses bounceout05.ispgateway.de and bounceout07.ispgateway.de.

Obviously these domains are not on my server.

I have tried searching the email logs for this address and similar ones with no results.
I have searched for the IP of ispgateway.de and its ranges in the email logs, without results.

Can you help me find out how this email is being sent from my server?

 

[WebHostingAce]

I think in the Sender Score they are referring to the reverse DNS (PTR) associated with your IPs.

To check this, you can use a website like DNS Propagation Checker - Global DNS Checker Tool . Simply enter your IP address, select 'PTR', and see if it resolves to bounceout05.ispgateway.de or bounceout07.ispgateway.de.

Most hosting providers allow you to modify the reverse DNS (PTR) for your server's IPs. I recommend checking with your hosting provider to confirm this.

For reverse DNS, you should be using a proper hostname. For example, if your server's hostname is server.yourcompany.tld, you should ensure the PTR record matches that hostname.

Make sure you also have an A record set up for the hostname you want to use. For example:

A record - server.yourcompany.tld
PTR record - xxx.xxx.xxx.xxx → server.yourcompany.tld

This way, your reverse DNS and A records will align correctly, helping improve your sender reputation.

 

[spg_nueve]

Hello, first of all, thank you for your quick response.

In this case the PTR of our server is correct and refers to our domain.

Could it be a mail service contracted by some of our clients?