we have a Microsoft Exchange server in our company that sends mail directly. However, the Exchange server is in Switzerland with a Swiss IP address and the actual online webserver (that also collects mail) [url removed, login to view] has an American IP address.
As a result, we are receiving many messages such as:
The e-mail system was unable to deliver the message, but did not report a specific reason. Check the address and try again. If it still fails, contact your system administrator.
<[url removed, login to view] #4.0.0 smt; 451-18.104.22.168 is not yet authorized to deliver mail from>
The following recipient could not be reached:
You do not have permission to send to this recipient. For assistance, contact your system administrator.
<[url removed, login to view] #4.7.1 smtp; 4.7.1 Greylisting in action, please come back later>
I assume that this has something to do with the PTR and / or SPF records on [url removed, login to view] / [url removed, login to view] domain. Looking for an experienced admin to solve this problem.