For our SFMC configuration we are using multiple Sender Profiles which should allow for the customers to reply, and have all their replies result in a case created in SF. One of the Sender Profiles is a dynamic one, configured using a content block which selects a set of From Addres+Reply To Address based on customer data in the Sending Data Extension. Email to Case is already set up and is working for email@example.com, firstname.lastname@example.org, email@example.com addresses which are configured to forward to SF specific addresses which handle case creation. This has been tested and works well.
We have requested the SAP to handle sending from Marketing Cloud. Our SAP subdomain is @communication.company.com. As we have multiple Sender Profiles with different Reply To addresses, including the dynamic one, we have set up RMM independently for all of them - using the 'Custom Reply Mail Management Settings' option in the Sender Profile configuration. For example we have set up the From Address to be firstname.lastname@example.org, checked 'Use custom settings below' in RMM settings and put email@example.com for reply forwarding in 'Use Specified Information' (this is just one option from the dynamic sender profile, the actual values in the settings are variables from a content block).
We have tested this setup and it leads to cases being created in SF when the customer replies, but not correctly linked to the contact as the from Addresses of the customer in SF becomes firstname.lastname@example.org@communication.company.com. Curiously, this issue occurs for all but one of our addresses, for which the cases do link properly and the from address of the customer remains email@example.com.
Is our setup correct? Or should we be using firstname.lastname@example.org, email@example.com etc addresses in replyTo? We tested this approach and it did not work, but we are wondering if that's due to some DNS changes we have missed but should have done. Does our existing set up has any impact on deliverability + the way the emails are forwarded?