Subscribers can be excluded at a list level or segment level when you're selecting which recipients to send a campaign to.
This is useful if you need to prevent certain subscribers from receiving an email because, for example, the content is not relevant to them or the thing on offer is not available to some of them.
Exclude a subscriber list
When preparing to send a campaign you'll notice, on the "Who will receive this campaign" page, an exclude option for each list. When you click Exclude list it means anyone who exists in that list, who also exists in another list you have selected, will not be sent the campaign.
Hover your cursor over a subscriber list to show the exclude button:
Let's say you wanted to send staff, volunteers and website members an email to promote an event. However, some people who have already registered could be on the lists you're sending to.
To prevent the email being sent to them, you click Exclude list for the registration list. Next, in the campaign snapshot, you see how many email addresses will be excluded from the campaign send:
Although there are 62 email addresses in the registration list, only 56 are marked for exclusion because that's the number of emails which also exist in the send lists: Staff, Volunteer Fundraisers and Website Members.
Exclude a list segment
You can also exclude subscribers at a segment level.
Here we want to email all conference attendees and past presenters, except for attendees who live in Australia; represented by the "Based in Australia" segment:
By excluding the "Based in Australia" segment, any matching email addresses found in the parent list (Conference Attendees) or the Presenters list will be excluded from the campaign send.