This button allows users to stop receiving any further emails. It is usually placed at the footer of the email. Making this button a bit fun can make a difference.
When someone clicks the unsubscribe button, you can take them to a funny unsubscribe page (depending on the target audience).
Make unsubscribing easy, let it be just one click. Making people do more steps (like logging in with their email, leading them to 3 different landing pages, etc.) can frustrate them. Moreover, avoid hiding the unsubscribe button.
Because not everyone wants to unsubscribe for the same reason, you can add a short survey to find out why. This input will give clear feedback. Analyze that precisely and take the data into account when creating email content in the future. Just make sure the survey doesn’t last long, as 1 sentence about the unsubscribing reason could be good enough.
Some people don’t want to unsubscribe, but they are just not active readers. One way to get them interested again is to send them a personalized email offering them a promo code (10-15 %).
If sending regular emails to your inactive subscribers is costly for you, send them an email where you kindly ask them if they still want to receive your emails. If they don’t even open it, send them another email with similar content after a while (for example 1 month). In case they ignore it again, unsubscribe them from your database manually - but just if this will decrease your sending costs.