Dynamic segments update automatically and immediately. Once you create a segment, it will pull members from all people in your account based on the definition you establish -- this is why it's important to confine a segment to a specific list if you are using it for a campaign email. Otherwise, you risk emailing people who have not opted in to receive marketing emails from you. While you're building your segment, you only have to set the conditions once.
There are two notable exceptions to the above:
- Segments that rely on relative time conditions, which are only true after a certain period of time -- these types of segments update every 24 hours instead of real-time
- Segments that rely on all "negative" conditions (for example, everyone that is not in several specified lists) -- these types of segments may update with a slight delay
Segments with Relative Time Conditions
Dynamic segments that are based on relative time conditions are updated every 48 hours.
For example, take a segment of people who haven't purchased in the last 30 days. This segment can only be computed periodically (there's no event triggered by not-purchasing). Likewise, a segment of people who purchased at least X times more than Y days ago can't always be computed from a purchase event.
Segments with All Negative Conditions
If you have a segment that only includes negative conditions -- for example, everyone that is NOT in several specified lists -- this segment may also update with a slight delay.
To optimize your segments for real-time updating, use mainly positive conditions as your primary filters to isolate those that do (vs. don't) meet a set of criteria.
How to Manually Update a Segment
If you would like to manually update a segment at any time, select the segment and click Edit Definition > Update Segment.