Use Configuration | MercuryS | Connection control and select the first two options to turn off relaying and to turn on strict local relaying.  You can then check the third option to allow and setup the auth password file that contains the username and passwords to be used to allow specific users to relay.

Hi

I try to set up mercury on my server which has a domain registered on it.

Works fine so far. I can receive and send emails. Problem is, that anyone is able to send mails without beeing asked for password or whatever. So spammers love my server -_-

 
I cant find any option to activate some kind of usercontroll for MercuryS . Just by IP, but this doesn't help me as my IP changes often ;)

Tried to use the "Authenticated SMTP connections my relay + Only auth ..." and added user + pw to a pwfile

Doesnt help ... ( as I dont want to relay anyway... )

I hope you can help me ;)

Greetings Sea