Most “false positive” comments, those valid comments that Akisment erroneously marks as spam, occur on new posts.

Typically, older comments are targeted by spam agents as these posts “fall off your radar” after awhile – you’re just not as likely to return to posts that are six months old as the topic becomes exhausted.  When spam agents attack these areas, you will receive notification of this repeatedly within your spam queue, which can become an issue for large blogsites.

When this Automatically discard spam comments on posts older than a month option is enabled, these notifications will not appear in your queue – Akismet will just automatically delete the spam and not tell you about it.

Configure Akismet

To configure Akismet, do the following:

• From within your Dashboard, click on Plugins > Akismet Configuration.
• Select the Automatically discard spam comments on posts older than a month checkbox.
• Click the Update Options button.