We are unable to send email to certain domains, this is the error:
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.
<mail.mydomain.com#4.0.0 smtp;450 <recipient address>: Recipient address rejected: Valid DNS required on connecting IP (external IP Address for our Exchange) [05NAPB0BUS00]>
We're using MX Logic to filter out email. I contacted MxLogic Support. They said I need to add a SFP record to my external DNS and this told to add "v=spf1 ptr include: mxlogic.net -all" as our SPF record.
Any ideas what the syntax would be for me to add to my external DNS (host by Network Solutions)