From the documentation:
How ERPNext handles replies
In ERPNext when you send an email to a contact like a customer, the sender will be the user who sent the email. In the Reply-To property, the email id will be of the default incoming account (like replies@yourcompany.com ). ERPNext will automatically extract these emails from the incoming account and tag it to the relvant communication
A. * Is there a way to setup erpnext, that the Reply-To will be the original sender?
B. * AND that ERPNext shall automatically extract these emails from the incoming account and tag it to the relvant communication?
If so, how?