I have received several emails from members (maybe maybe not members?) and it's from a .... Do not reply at NLG email address.
Myself or others can't respond to those emails. Not sure how they are sending the messages.
They are using the "Mail this user" button below your name on your posts. The From address is the "no reply" address, but the Reply-to address embedded in the message is the user's actual e-mail address. Your mail client should correctly see that and use it when you click the Reply button.
If you wish to disable the feature, go to
your Account Settings and untick the checkbox that says "Allow uses to email me", then click the "Change profile" button in the lower right to save your changes.