I have a virtual server with one IP x and have multiple sites a.com and b.com running on it.
When accessing x in the browser, I get to homepage a.com.
Sending an e-mail from a.com to GMX is without any problems. Sending an e-mail from b.com to GMX leads to following error:
host mx01.emig.gmx.net refused to talk to me: 544-gmx.net (mxgmx101) Nemesis ESMTP Service not available 554-No SMTP service 554-Bad DNS PTR resource record.
I contacted the hoster which told me to setup something called "Reverse Delegation" to point the IP x to b.com. But don't I just shift the problem?
What is best practice for sending e-mails from a shared hosting environment?
Regards, Rokko