What happened
After my WordPress 1.5 upgrade and enabling of an option to reject comments from open proxy, no comments (over 100) were appearing on my blogs. Moreover they were silently discarded.

Details
I recently upgraded to WordPress 1.5. WordPress has an option to specify keywords in a blacklist. Any comments matching those keywords will be automatically and silently deleted from the blog. Fortunately the comments still remained in the database tagged as spam.

Yesterday I found out that even my comments were being silently discarded. On investigation I realized that WordPress 1.5 option to blacklist comments from open and anonymous proxy is defective. It simply discard any comments silently, treating them as spam. Talk about over enthusiastic spam gobbling!

My solution
To recover I simply went to the database using phpMyAdmin, deleted whole bunch of poker, viagra and medicine spams by hand, in the process blacklisting several additional domains like doobu and vpshs. Finally I changed the status of 100 or so valid comments so it show up on my blog.

Additionally I unchecked the (culprit) option to Blacklist comments from open and insecure proxies.

Workaround for WordPress defect
Please uncheck the option to Blacklist comments from open and insecure proxies in the Options/Discussion tab.

Check your database to manually approve valid comments and delete the rest (spam).