Anyone who requests membership of a list has a record created for them. This record contains details of their current status, whether they are allowed to post to the list, whether they want digests sent, when they became a member, etc. In addition, each record indicates whether the
record is active – that is, whether email messages should be sent to that address.
When someone leaves a list (perhaps because they choose to, their membership has expired, email to them is returned, etc.) the record is marked as inactive. This means that list owners can offer list membership to people for a given period of time (say three months) and prevent them re-joining the list in the future (perhaps when they have paid a fee).
GMS Communication Server is licensed on the number of records that are maintained by a list. So if there are 1250 active members on a list and 250 leave, 100 are suspended and 600 join, there will be 1250 + 600 = 1850 records but only 1250 – 250 – 100 + 600 = 1500 active members. If a message is posted to the list, only the first 1500 records will be processed so there are a potential 350 people who will not receive the message.
Inactive records can be removed (or purged) from the list at regular intervals or on demand by using the GMS Communication Server administration interface.