Sending and Receiving Messages

Hi everybody,

i am having issues with replying to customer messages who reach out after buying a produkt. My answer via the message-board get's the status "Nicht zugestellte Nachricht, klicke hier für weitere Informationen.! (My Translation: Message could not be delivered, click here for more information). the information profided is the FAQ and has nothing specific.

So right now i get bad reviews for not answering my customers. I already submitted Requests via Chat/Mail direct to amazon - but only get template answers which are not slightly refering to the problem.

Little Backstory: The Account was blocked in the past due to an accout-theft and was re-enabled after changing credentials and everything. But the message-board is broken since then...

Any advice or support from you guys?

I am aware that customers can opt out of receiving notifications about messages from sellers - i am not sending messages to "random" customers. I want to answer in the message-board to there questions - mostly delivery.