we have the issue, that all of our Emails to a certain email client (gmx.de, gmx.at, web.de based by 1&1 Mail & Media GmbH) are listed as Spam and are not delivered and we get a bounce.
In a first check i could see, that the server Ip where the Emails where send is : 22.214.171.124 and that this IP is Blacklisted on SORBS Spam List.
I can not directly identify if this Blacklist is the reason why we cannot send Emails to our clients.
Does anyone know how we can solve this problem. Unless we are not able to send emails to our clients.