Cannot send mail messages from Plesk server. Client host rejected: cannot find your reverse hostname

Symptoms

• Mails are not sent to a specific address.

• The following messages can be found in the /var/log/maillog file:

  CONFIG_TEXT: Reason: Remote SMTP Server Returned: 550 5.7.0 Your server IP address [203.0.113.2] is missing a reverse DNS entry

• The following messages can be found in the %plesk_dir%Mail Servers\Mail Enable\Logging\SMTP\SMTP-Activity-XXX.log:

  CONFIG_TEXT: ME-IXXXX: [0A9BDE4490704C08A66604721DC0C96B.MAI] Remote server returned a response indicating a temporary failure. Server Response: (450 4.7.1 Client host rejected: cannot find your reverse hostname, [203.0.113.2])

Cause

Reverse DNS zone for the affected IP address and domain does not exist.

Resolution

Reverse DNS records should be created by the owner of the IP address. Usually, it is a Hosting service provider or Internet Service Provider (ISP). Contact IP address provider and request to create reverse DNS zone for affected IP address and domain.