Unfortunately, spammers have the possibility to deliver messages directly to your mail server without being checked by our filter and thus cause spam. Therefore you should set your mail server to accept only messages that have been checked by our filter.
In order to ensure that only messages from the EuropeanMX cloud are accepted on your mail server, it is best to use the address "delivery.antispamcloud.com" for approval. This hostname contains all active IPs and can be used as reverse DNS for the delivering IPs. For redundancy reasons, we have divided our EuropeanMX cloud between different data centers and networks. As we regularly expand the EuropeanMX cloud, new IPs may be added on a regular basis. You can find a list of IPs on our website https://europeanmx.eu/en/mxstatus.
Please also make sure that your firewall does not block DNS port 53 TCP (to avoid reaching the UDP packet size).
If you are unable to enable sharing via a hostname then you can alternatively set your mail server to listen on an alternative server port, e.g. port 2525 instead of the default port 25. You can set the special port in your Eunetic account under the hostname of your destination server. To do this go to your Eunetic account and click on "MY BUYS" > "Email Filters". In the overview please click on the green button with the three small white dots and select "Edit". Click on the button "Change previous settings" to change the settings for your domain. Under "Destination mail server" you can now enter the new port.