Hi Kyriakos,
There is a component - BT126H_MAIL which opens a screen from where you can send emails. I think this is the scenario for Customer Service Representatives if they which to reply to customers or want to send an in house email from the Web UI.
I'm not sure if this will provide solution to your requirement, but thought of sharing this information.
Hope this helps.
Thanks,
Samantak Chatterjee.