I want to send out an email to all customers currently sitting in our ‘newsletter ‘ group asking them to opt in / subscribe to being in new 'Event & training group / Updates & information group...etc. We are getting ready for GDPR / 25th May.

What would be the easiest way to do this? Has anyone got any examples of how they have done this were customers have just clicked on a links and they have then automatically ended up in a group?

Thanks Anna