The Stop the War Coalition (STWC) took a different approach to the EU’s ‘General Data Protection Regulation’ (GDPR) from most anti-war/peace organisations.
By 25 May, as one part of GDPR, organisations in the UK (commercial and non-commercial) were meant to make sure they had explicit, positive permission from everyone on their email lists to keep their data and to keep sending them emails. (If someone has joined your group as a member, that counts, for example.)
Some peace groups sent out fancy one-click consent buttons. Others, like PN, made you go to their site and type your email address in (and maybe click on a confirmation email as well). The GDPR says ‘silence, pre-ticked boxes or inactivity should not constitute consent’.
STWC sent out an email on 11 May only giving people the option to unsubscribe. Maybe this showed confidence that it’s already in compliance.