Before a Comment Appears

The two options in the Before a Comment Appears section tell WordPress
how you want WordPress to handle comments before they appear in
your blog:
✦ An Administrator Must Always Approve the Comment: Disabled by
default, this option keeps every single comment left on your blog in
the moderation queue until you, the administrator, log in and approve
it. Select this check box to enable this option.
✦ Comment Author Must Have a Previously Approved Comment:
Enabled by default, this option requires comments posted by all first-
time commenters to be sent to the comment moderation queue for
approval by the administrator of the blog. After comment authors have
been approved for the first time, they remain approved for every com-
ment thereafter (this cannot be changed). WordPress stores their e-mail
addresses in the database, and any future comments that match any
stored e-mails are approved automatically. This feature is another mea-
sure that WordPress has built in to combat comment spam.