The list header setting of Default-Options=SUBJecthdr is the default setting for new lists. See the List Subscribers FAQ "How are the mail headers determined on messages that I receive?" for details on mail header defaults and options.
To change the mail header style for your list, you will need to change the default mail header option for both new and current subscribers:
To change the mail header style for your existing subscribers to the IETF-style:
- Address an e-mail message to email@example.com (or select List Management | LISTSERV Command from the web interface)
- Put the following command in the body of the message:
quiet set listname IETFhdr for *
To change the list header setting to Default-Options=IETFhdr for all new subscribers, using the web interface:
- Select List Management > List Configuration > Manual List Configuration
- Change Default-Options= Repro,SUBJecthdr to Default-Options= Repro,IETFhdr
- Click Submit to update the header configuration.