Refreshing a Segment
The number of contacts in a segment is worked out on a schedule rather than continuously. The count shown on the Contacts page and on the segment page is therefore the result of the last calculation, not a live reading of the store. A contact added, edited or deleted since then is not reflected in the number until the next one runs.
The conditions themselves are always in force. A campaign that targets a segment sends to the contacts that match it, and the count is a reported figure that trails slightly behind.
Next Refresh and Last Refreshed
Every segment is recalculated once a day, so the count on screen is at most a day old unless it has been refreshed since. A new segment is populated as soon as it is saved rather than waiting for that cycle.
The segment page shows two timestamps.
Next Refresh gives an approximate countdown to the next scheduled calculation rather than an exact time, in bands such as under an hour, one to twelve hours, or twelve hours or more.
Last refreshed shows how recently the last calculation ran, which is the age of the count on screen.
Before a Run Sends
A campaign run that targets a segment recalculates that segment before it works out who to send to, so the recipients come from current membership even when the count on screen is older. The daily cycle and the on demand refresh govern the reported figures, not the send itself, so there is no need to refresh a segment purely to make a run accurate.
This applies up to the point the run's messages are built. After that the run sends the messages it has, and refreshing the segment changes the count and the runs built from it afterwards rather than that one. See Once a run has messages.
Refreshing on Demand
Refresh on the segment page starts a calculation straight away. Use it after a bulk upload, or after a round of edits that should change who matches.
A segment can be refreshed on demand twice a day, and no more than once an hour. The hourly limit applies whether or not the day's second refresh is still available, so two refreshes cannot be run back to back. Once either limit is reached the control is unavailable and explains why, and the daily allowance comes back with the next scheduled calculation.
Who Can Refresh
Refreshing is not restricted by role. Anyone who can reach a control that triggers one can use it, including a Campaigner.
Where the control sits does differ by role. A Campaign Manager or an administrator refreshes from the segment page in Contacts. A Campaigner does not see Contacts at all, so their route is the audience summary on a campaign or on a run, which carries its own Refresh now. See Roles and Permissions.
Triggering a refresh is separate from managing a segment. A Campaigner cannot build, edit, duplicate or delete one, and cannot open the segment page. See Segments.
An export refreshes the segment before the file is produced, so the contacts in an exported CSV are current even when the count on screen is not. See Exporting a Segment.
When a Refresh Fails
A calculation that does not complete leaves the segment on its previous count. The recommended action is to refresh it on demand, and a segment that keeps failing should be raised with an administrator.
A campaign run against a segment that could not be recalculated does not send, because its recipients cannot be worked out from stale membership. The run returns to Ready to Run rather than failing outright, and an email about the failed refresh goes to the person who started the run. Start it again once the segment refreshes. Nothing restarts on its own, because the alternative is sending to a stale audience.
The email a Campaigner receives leaves out the link to the segment, because the segment page in Contacts is not open to them. The refresh itself is still theirs to trigger, from the audience summary on the run. See A segment that could not be refreshed.