Object workflow email response doesn't reach B2B

Summary:

Object workflow was used to send email notification to customer upon Service Request record creation. Once the customer replies to it, the email sent out doesn't get to B2B Service.

Can workflow be used to reply and does it also function similar to Service Request Message feature?

Content (please ensure you mask any confidential information):

Screenshot of the email header received by customer. When they hit reply, message is sent out but doesn't arrive Fusion Service

Version (include the version you are using, if applicable):

24C

Code Snippet (add any code snippets that support your topic, if applicable):