Sources:

neilpatel.com/blog/high-email-unsubscribe-rate

www.emailmonday.com/smart-email-marketing-segmentation-the-art-of/

sumo.com/stories/email-unsubscribe-rates

sleeknote.com/blog/reduce-email-unsubscribe-rates

blog.autopilothq.com/why-people-unsubscribe-from-emails/

blog.jumplead.com/8-ways-to-minimize-your-email-unsubscribe-rate

www.outboundengine.com/blog/understand-the-importance-of-unsubscribes-in-email-marketing