Status: Public Preview — behaviour may change.

What it does

Lets you change the definition of a segment that a live journey depends on, without stopping the journey or creating a new journey version. The new membership flows into the journey at the next segment refresh.

Key facts

• It's off by default. An administrator turns it on under Settings > Overview > Feature switches > Segmentation, using Edit live segments used in live journeys. With the switch off, segments that journeys or other segments depend on stay locked.
• Editing a segment nothing depends on works as before. For an in-use segment you get two extra dialogs: Edit in-used segment lists the dependent journeys and segments, and Preview member changes and save shows an estimated member count and which journeys are affected.
• Your edits live in your browser until you choose Save or Create a copy. Close the tab and they're gone. Other users keep seeing the published definition meanwhile.
• Saving republishes the segment only. The journey keeps its start date, analytics and history, and no new version appears. Editing the journey itself still creates a new version.
• Timing depends on journey type. One-time journeys only pick up a change if the segment recalculates before the audience snapshot. Recurring journeys apply it from the next occurrence. Ongoing and trigger-based journeys pick it up at the next refresh.
• Segment role matters. Exclusion segments affect only people admitted after the refresh. Exit (suppression) segments are checked at every step, so they act fastest.
• Narrowing a segment doesn't remove people who already entered the journey. They carry on and finish it. Use an exit segment to pull them out.
• A refresh already running finishes on the old definition, so members matching the previous query can still arrive just after you save.
• Static groups inside the segment go read-only during live editing: no CSV upload, no new manual list, no member changes, no deletion.
• Each segment now shows when its query last changed. The segment size chart marks Current edit and Previous edit, and the side pane shows Last query change with the editor's name for the latest one only.

When to use / skip

Use it when the journey design is right and only the audience definition is wrong: a missing exclusion, a typo in a query, a stakeholder widening the target. It saves you the stop, new version and restart cycle and keeps one set of analytics.

Skip it when the audience and the journey design both need to change. Edit the journey as usual. Skip it too for a campaign where a mid-flight audience change would be a compliance problem, and use Create a copy instead.

Configuration decisions

• Who gets to edit. Decide who is trusted to change in-use segments before you flip the switch, because the feature switch is tenant-wide in effect.
• Edit versus copy. Agree a rule of thumb for when a change goes in place and when it goes into a copy.
• Exit segments up front. If you expect to need to stop people mid-journey, build an exit segment into the design rather than relying on narrowing the entry audience.
• Nested segments. Decide whether teams edit child segments or the parent directly, since child edits take two evaluations to reach a journey.

Gotchas

• Nothing recalculates on save. The change waits for the next execution, then for the journey to read it.
• The member count in the save dialog is an estimate, not a preview of exact membership.
• Concurrent editing isn't protected. Two people editing the same segment can overwrite each other.
• Segments that originate in Customer Insights - Data are still edited there, then need a data refresh and sync before a journey sees them.
• It's a preview feature, so don't build an operating procedure around it for a regulated send until it reaches general availability.

Consultant notes

• The biggest surprise is that tightening a segment doesn't eject anyone. Business owners assume "I removed them from the segment" means "they stop getting emails", and it doesn't. Say so in the handover.
• Put the dependency dialog in your change process. Whoever edits a segment feeding five journeys should have looked at that list first, and a screenshot in the change ticket is cheap.
• For one-time sends, schedule edits well ahead of the run and confirm the recalculation has completed. A late edit just misses the snapshot and nobody notices until after the send.
• Use the Current edit marker on the segment size chart when someone asks why the audience jumped. It answers the question faster than digging through journey history.

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Preview feature — worth revisiting when it reaches general availability or the feature switch default changes.