What is a segment?
A saved set of rules that works out who matches every time it's used: how segments differ from lists, and where they're used.
A segment is a saved set of rules (status, list membership, tag, signup date, engagement) that works out who matches at the moment it’s used. It holds no contacts of its own. “Subscribed contacts on the newsletter list who clicked something in the last 30 days” is a segment; who’s in it today isn’t who was in it last month, and that’s the point. Segments live on their own Segments page in the sidebar.
Segment vs list
| List | Segment | |
|---|---|---|
| Membership | People are added and removed | Worked out from rules, every time |
| Consent | People sign up and opt out of it | None of its own |
| Signup forms | Point at a list | — |
| Goes stale | Only if you let it | Never |
| Deleting it | Removes memberships | Removes nothing but the rules |
Deleting a segment deletes no contacts. It’s a saved question, not a container.
Where segments are used
- On a campaign, as Also send to a segment under the audience step’s More targeting section.
- On the contacts page, as the All segments filter, which also drives what Export produces.
- In an automation, as a condition step’s rule.
Segments add to lists, they don’t filter them
On a campaign, the audience is the target lists plus the segment, deduplicated. It is not “the segment narrowed down to the list”. Somebody who matches both gets one email. For a narrower audience, put the list into the segment itself: add a rule for List is in your list and leave the campaign’s list selection empty.
Consent still wins
A segment can’t route around an opt-out. When a campaign targets a list, anyone who opted out of that list is excluded, even if they match the segment. Suppressions and unsubscribed statuses apply on top of any rules you write.
The match count is a snapshot
The Matches column on the segments table is a cached number: a green dot means it was counted since you last edited the rules, an amber dot means the rules changed after the count. Treat it as approximate. The count in the builder is live, and every send re-runs the rules from scratch.
Limits
- Up to 20 rules per segment.
- Engagement rules look back at most 90 days. See Why engagement rules only look back 90 days.
- Rules cover status, lists, tags, signup date and engagement. There’s no rule on custom-field values; tag the contacts instead.