Dear Farhan Zafar1,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
To ensure that your client's Microsoft Exchange emails continue to work after redirecting the domain to Hostinger, you will need to update the DNS records for the domain.
Log in to your GoDaddy account and go to the DNS management page for the domain.
Locate the MX record for the domain and take note of the current settings.
Log in to your Hostinger account and go to the DNS management page for the domain.
Create a new MX record with the same settings as the one you noted in step 2.
Save the changes and wait for the DNS propagation to complete.
Once the DNS propagation is complete, your client's Microsoft Exchange emails should start working again. If you encounter any issues, you can contact Hostinger's customer support for further assistance.
I hope this helps! Let me know if you have any further questions. Please understand that our initial response may not always resolve the issue right away. However, with your help and more detailed information, we can work together to find a solution. Thank you for your help.