Hi,
I currently have my mailserver set up to redirect all incoming mail to my GMX account as well. Apparently they enforced SPF now and people sending me messages get the following message as well:
This is the mail system at host my.mailinabox.server. I’m sorry to have to inform you that your message could not be delivered to one or more recipients. It’s attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system mygmxaccount AT gmx.de>(expanded from email ATmy.mailinabox.server): host mx00.emig.gmx.net[212.227.15.9] said: 550-Requested action not taken: mailbox unavailable 550-Reject due to SPF policy. 550-The originating IP of the message is not permitted by the domain owner. 550 For explanation visit http://postmaster.gmx.com/en/error-messages?ip=xxxxxx&c=spf (in reply to MAIL FROM command)
Reporting-MTA: dns; my.mailinabox.server X-Postfix-Queue-ID: C30798901B54 X-Postfix-Sender: rfc822; user@thatwrote.me Arrival-Date: Wed, 8 Jun 2016 10:01:36 -0400 (EDT) Final-Recipient: rfc822;mygmxaccount@gmx.de Original-Recipient: rfc822;email@my.mailinabox.server Action: failed Status: 5.0.0 Remote-MTA: dns; mx00.emig.gmx.net Diagnostic-Code: smtp; 550-Requested action not taken: mailbox unavailable 550-Reject due to SPF policy. 550-The originating IP of the message is not permitted by the domain owner. 550 For explanation visit http://postmaster.gmx.com/en/error-messages?ip=xxxxxxxx&c=spf
I tried looking up the issue but unfortunately could not find anything in that regard. How can this be fixed?
Thanks! 
