Our company's email is flowing fine but a user has a problem sending to a certain address - here is the error message in return.
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.
< barracuda.domainname.com #4.0.0 X-Spam-&-Virus-Firewall; host mail.receivingdoaminname.com[public IP] said: 421 Refused. Your reverse DNS entry does not resolve. (in reply to RCPT TO command)>
so they refused email from our domain because our reverse DNS entry does not resolve.
Im saying were fine because we can send to everyon eelse without problems and I went to mxtoolbox.com and entered our outgoing mail public IP addess (ptr record IP) and it resolved fine to our domain name which it listed as barracuda.domainanme.com TTL 3HRS
So what could be the problem?