AntiSpam module is the successor of the Akismet module, and it provides spam protection to your drupal site using external antispam service like Akismet.
AntiSpam module is fully compatible with Drupal 6.x (Akismet module for Drupal 6.x release had many compatibility issues and was not usable as it was), and it expanded the support of the external antispam service with TypePad AntiSpam and Defensio service as well as Akismet service. Now you can choose one of the antispam service you wish to use.
There are known major bugs in the current "stable" release, it is suggested to use the dev release until v7.x-1.6 can be released.
Supported Anti-spam Services
In case of Defensio, the AntiSpam module take advantage of spam rating (spaminess) information provided by Defensio and you can sort the moderation queue list using spaminess (see the screenshot).
AntiSpam Helper Module
We have developed AntiSpam Helper Module, which is designed to be used with AntiSpam module. Currently, it has only one feature. It checks the number of published nodes/comments by a user and if a user has posted certain number of posts, it automatically upgrade the user's role to the specified role. All you need to do is create a new user role which does not require spam checking upon node/comment submission, and set the minimum required number of posts to be eligible for upgrading to the role. This AntiSpam Helper module is currently available at the article of the following issue.
Automatic Whitelisting Members
AntiSpam 1.0 has introduced a new API function called antispam_api_cmd_spam_check() so that other modules can check any text data user entered using an external antispam service configured by AntiSpam module.
function antispam_api_cmd_spam_check($body, $name=NULL, $mail=NULL, $homepage=NULL);
$body - text data to be checked
$name - (optional) author name
$mail - (optional) author email
$homepage - (optional) author homepage
-1: Error (connection to external service failed, text is too short, etc)
0: The text is HAM (not spam)
1: The text is SPAM