diff --git a/app/models/email_domain_block.rb b/app/models/email_domain_block.rb
index d52c76b030..c4ab8b9ed2 100644
--- a/app/models/email_domain_block.rb
+++ b/app/models/email_domain_block.rb
@@ -70,7 +70,7 @@ class EmailDomainBlock < ApplicationRecord
         segments = uri.normalized_host.split('.')
 
         segments.map.with_index { |_, i| segments[i..].join('.') }
-      end
+      end.uniq
     end
 
     def extract_uris(domain_or_domains)