Installing DKIM and SPF records
The reason for doing this is to get the Action Network software to recognise your domain which will improve the delivery rates to inboxes (rather than going to jumk/spam).
The extinctionrebellion.uk domain has already been set up. So if you use an email address as your reply-to email, then you don't need to do anything. You can apply for these email addresses here.
It is not possible to do this for gmail/hotmail/aol/outlook etc reply-to email. These should be recognised domains.
But if you have your own domain e.g. xrnottingham.org, then it is worth reading this guide below and following the instructions.