[otrs] customer Follow-Up notificatio after agent update via e-mail

Hi folks, I've been trying to set up a queue where agents update ticket status via e-mail but when doing so, customer who created the ticket, does not get the follow-up message as if the agent would have updated the ticket via OTRS web interface. I'm using OTRS 2.3.4 and have set up X-OTRS-FollowUp-SenderType to agent and in the web interface, OTRS detects the e-mail update as coming from an agent. The only missing part is the notificatio to the customer containing the message sent by the agent. Is it possible? Can anyone shed some light on this issue? Thank you very much in advance, Samuel.