List Types in HaleyMail

On the list management screen some lists are listed as system lists, some as dynamic, and some have a number next to them.  Can you explain what the difference between these three kinds of lists are?

A system list is built by the HaleyMail system and is reserved for newsletter mailings. They can not be deleted.

A dynamic list is one defined with parameters and the contents vary as the users in the database change. For example, a list of everyone with the last name 'Smith'. OK - that's a small list that doesn't change much :) But whenever anyone with the name Smith is added, they would become part of this list. BY their nature, the number of contacts on the list is dynamic, and can vary right up until the moment the mailing is sent, even after is has been scheduled.

A static list are those lists with numbers next to them. These lists are usually built by uploading a list. These are static, in the sense that they only change when an administrator adds or removes contacts. Because of this, the count is known at all times.