How to send a campaign to a segment
When creating a campaign, you can send it to a segment of your list you created earlier. To do that, simply click on the "Segment" tab
Using multiple segments in one campaign
If you want to include or exclude multiple segments in a campaign, go to the “Advanced” tab, choose "Segments" from the first condition field, and then choose a specific condition modifier and segment.
Using segments in scheduled campaigns
When you send a scheduled campaign to a segment, the end list of recipients will be determined at the sending time. If new subscribers end up being included in a segment after you scheduled the campaign, they will be included as recipients when the sending time comes. Conversely, if someone no longer meets the segment conditions by the time the campaign is scheduled to be sent, they won’t be included.