A clean email list is when only active and engaged subscribers remain on an email list.

Having a clean email list ensures maximum campaign effectiveness, since open rates and engagements will be higher.

Inactive contacts are considered those who haven't opened a campaign in the last 6 months.

It is also possible to identify inactive or disengaged subscribers by sending a re-engagement campaign. Those who do not respond can be removed from an email list.

Likewise, any contacts which don't wish to remain on a list can also opt-out.

Another benefit of having a clean email list is that it is better for the planet, since companies will have lower carbon emissions as a result of sending fewer unnecessary emails.