A closed list requires the owner to approve all new subscribers so a closed list takes more time depending on the size of your prospective audience. A moderated list requires the owner to approve all postings which would also take time. You can request 'sub-list capabilities' for your list from the list hosting server's technical support. The list owner decides who can post messages. Posting can be limited to the owner, a group designated by the owner, or any subscriber.
Postings can also require an owner's approval.
Attachments can be sent via a list but they cannot be posted from the web interface. Attachments must be sent to the list from the subscriber's desktop e-mail software. Unless it is a public list, only subscribers to the list can see or search the archives. A list's archives can be kept as long as the list is active. Archives will normally be deleted upon cessation of a list unless other arrangements are made.