We have not had any issues with our exchange server in the past but the users are now trying to contact a new email client and are receiving an error message - see below:
"There was a SMTP communications problem with the recipient's email server. Please contact your system administrator. <exchange server name.domain #5.5.0smtp;554. This server requires PTR for unauthenticated connections.>"
I have contacted our ISP and they have added an "A" record in our DNS list pointing to the name of the exchange server.domain and the routable IP address assigned to the exchange server. We still get the same error message. What would I require to do to be able to send email?