I am trying to send email from a MS Exchange Server to a Netfirms domain but I get this error:
mx1.netfirms.com rejected your message to the following e-mail addresses:
Mario Lopez (firstname.lastname@example.org)
mx1.netfirms.com gave this error:
sorry, that address cannot accept mail from an unresolved IP address
A problem occurred during the delivery of this message to this e-mail address. Try sending this message again. If the problem continues, please contact your helpdesk.