Hi Mani,
This issue likely started because of changes in Microsoft 365 security policies.
By default, Microsoft blocks automatic forwarding to external domains to prevent data leaks or spam abuse.
You can allow automatic external forwarding by changing a setting in Exchange Online:
- Go to Microsoft 365 Security & Compliance Center: https://security.microsoft.com
- Navigate to: Policies & rules > Threat policies > Anti-spam policies
- Open the Default (or custom) anti-spam policy.
- Under Outbound spam filter policy, find the setting: "Automatic forwarding".
- Change it from "Automatic - System Controlled" or "Off" to: "On - Allow automatic forwarding".
- Save the policy.
You can check this - https://learn.microsoft.com/en-us/defender-office-365/outbound-spam-policies-external-email-forwarding
Let me know if you have any query.