SP-API: Automation of Seller-Buyer Messaging and Returns Communication (Read/Reply)

[amoreux2084]

We're exploring the possibility of integrating a custom AI agent for full, contextual automation of customer service replies.

Our goal is to use the Selling Partner API (SP-API) to allow our hosted AI to both read and send replies to customer messages in the following areas:

1. General Buyer-Seller Messages (The 'Messages' inbox).
2. Messaging within 'Manage Seller Fulfilled Returns'.

Core Question: Are there specific endpoints in the Messaging API or Returns API that permit this two-way communication (read and reply) for these message types?

Has anyone successfully achieved this level of automation for both message types? Any insight on 3rd-party tools that currently offer this functionality would also be appreciated.

Thanks for any technical guidance!