Graham, Were the subscriptions on this list all added prior to adding that Default-Options keyword in your list’s header? I ask because it only applies to future subscribers. To apply that option to existing subscribers, you need to set that option manually for each subscriber or issue a batch type of command to set it for everyone, as in “quiet set X SUBJECTHDR for *@* on the Listserv command line, where X is the name of the list. On Jan 28, 2016, at 10:16 AM, Graham Tolliver <[log in to unmask]<mailto:[log in to unmask]>> wrote: Hello, The subject-tag doesn’t show up in the subject. We are using ListServ 15.0. Here are the two lines in the configuration to achieve the task: Default-Options= SUBJECTHDR Subject-Tag= “Testing” Any assistance would be greatly appreciated.