@hosting @samsteiner Thank you for offering. I have not gone the Postfix route yet but I have been seeing the same spam pattern on my end in the last weeks. Currently I am using a combination of NGINX pattern detection of multiple registrations with failed email delivery in a short period of time to block registrations to the UA. It’s helping to somewhat mitigate it but I’m still not happy with the solution. Will continue to explore alternatives. Welcome suggestions.