A few weeks ago I implemented the recommendations on this forum to cut down on spam in including the barracuda RBL. It worked great. But now I am finding some people who were able to email me are getting their emails bounced back with this type of error. Connected to 18.104.22.168 but sender was rejected. Remote host said: 550 Authentication is required for relay Is there a setting I need to do to make sure people are able to email me? Also, I have one client who said that he can email the rest of the world fine, but when he emails his wife on the same domain they don't get through. Any ideas on if I did something wrong?