Rebuild PTR / Reverse DNS Cache and Update Mail HELO for Email deliverability

Symptoms

After updating the PTR record for the server's hostname, Email Deliverability is still showing the old PTR record. The interface also indicates the record doesn't match.

CONFIG_TEXT: The system uses an alternate HELO of “oldPTR.hostname.com”
when sending mail from the “server.hostname.com” domain.

CPANEL_WARN: "oldPTR.hostname.com" and "server.hostname.com" represent the previous PTR record and current hostname, respectively.

Cause

cPanel will automatically define the Mail HELO to match the PTR record for the server's outbound SMTP IP addresses. When the PTR record changes, rebuilding the cache would ensure the updated record appears in the Email Deliverability interface.

Resolution

1. Log into WHM as the root user.
2. Navigate to Home / Service Configuration / Exim Configuration Manager.
3. Click the Domains and IPs tab.
4. Click the Rebuild RDNS Cache button.

Additional resources

Exim Configuration Manager - Basic Editor - Domains and IPs