Email just stopped working

It was okay on Sunday, now it is bouncing and unable to send. Here's the test send message:

Code: [Select]

Your message did not reach some or all of the intended recipients.

      Subject: Email testing
      Sent: 2017-12-19 19:30

The following recipient(s) cannot be reached:

      '***********@gmail.com' on 2017-12-19 19:30
            Server error: '450 4.7.1 Client host rejected: cannot find your hostname, [24.239.14.203]'

Any ideas?

Note: Can still log into round cube and see the email addresses on the server.

Doug

I think this issue might be due to incorrect PTR record:- https://mxtoolbox.com/SuperTool.aspx?action=ptr%3a24.239.14.203&run=networktools so fix this issue first and then try to send/receive emails.

Thanks for the reply, but I don't think that's the issue.

The IP address listed is my home IP, not the server, it is at 23.111.69.102.

Any ideas about that?

Regards,
Doug

PTR Record point to domain (daowen.pub), not to host