A customer exits a Series when they meet any of the criteria you’ve specified in the Exit rules setting when building your Series:

Once a customer matches these exit rules, they cannot re-enter a Series.

If a customer reaches a rule block they do not match, or a message they don’t come online to receive, they’ll wait for the period specified in the block:

After this period, if they still haven’t received the message or matched the rules, they’ll be marked as disengaged and leave this path. 

If they’re in other paths in the series, they will continue down them.

If they match the rules to enter a different path in future, they will enter, but cannot re-enter the path where they became disengaged.