Hi Florent,I hope you are well.I am experiencing a similar issue where I am implementing the List Unsubscribe setup in my deliveries. I have used the code you supplied: <% if ((recipient.domain == 'gmail.com')|| (recipient.domain == 'gmail.co.uk')){%> Precedence: bulk <%}%>List-Unsubscribe: <%@ include option='NmsEmail_DefaultErrorAddr' %>?subject=unsubscribe<%= escape(message.mimeMessageId) %>>This code is working in the Gmail but not in hotmail/ outlook. I have even tried stripping off the if ...