pedjas

If you use Akismet, you are likely happy how it recognizes spam, but probably it still bothers you that you have to check recognized spam and reject it. If your blog is target of heavy spam, you may get large number of spams a day, and although Akismet prevents spam to show up on your blog, you still have to administer (delete) it.
Stop Comment Spam jumps in that place. It is very likely that you may identify large amount of spam by very precise keywords, and if spam contains specified keyword, it may undoubtedly be considered as 100% spam and rejected without need for Akismet or you to interfere.
For instance, my blog is overwhelmed by, what we call Russian spam. Thing is that my blog uses Cyrillic alphabet, and Russian spammers recognize that, so they pay more attention to spam it with comments containing Russian language. As my blog is not in Russian language, I needed tool to recognize if Russian language is used in a comment, and if that is the case, to simply reject it. That is how this plugin became. It also helps a lot with Chinese spam and other verious automated spammers.
You may use it to prevent using obscene words or other unwanted words in comments posted on your site. You just define list of words that are unacceptable, and any comment containing any of them would be rejected.
Also, you may set similar keyword rules for comment author web site URL. If you have some nasty spammer that is persistent to advertise his site, you just put his site url in forbidden url list and he is gone, any comment using that site as commenter site URL will be rejected.
There is option to limit number of allowed links in comment text. That would help stopping link spammers. All you have to do is set number of allowed links within comment. If spammer posts one more than allowed, his comment will be refused.
This plugin is simple and straightforward. It will help you to filter out exact words or phrases, but it is not strong against more profane spammers. But, that is what Akismet is for. This plugin works as Akismet companion. It filters out obvious spam and lets Akismed deal with rest.
Author uses this plugin personally since year 2009, and it prooved to be very helpful. It stopped two times more spamm comments than Akismet. This does not mean Akismet is worse, just that two thirds of spam comming to my blog were so obvious that simple tool like StopCommentSpam could handle it leaving Akismet to deal with less but more delicate spam.
<h3>Keyword examples</h3>
To stop spam comments using Russian language add these as forbidden comments contents:
ы
ю
щ
я
э
ь
й
ё
пасибо
что
все
Все
Мне
мне
автор
Что
To stop some spam linking to spam or malicious sitees ad these to forbidden URL contents:
.cn
healthcare
drugstore
mail
loan
finance
insurance
viagra
baidu.com
clearance
forum
xxx
topic
gscraper
jimdo
nikeschuhe
jordan
discount
money
pharmacy

Stop Comment Spam

Stop Comment Spam treats any comment by predefined rules to stop spam. It is supposed to be used as additional measure for any other antispam tool esp …

willjenkins

Using the most effective features of other spam programs. Astounding Spam Prevention effectively guards against comment spam and registration spam without the use of a Captcha. 
This is a fork of the original Stop Spammers Spam Prevention and uses some of the code, but it is greatly simplified so it is not as aggressive and will not prevent a user from logging in. It does not interfere with jetpack and does not know about WooCommerce so there are no conflicts. Unlike Stop Spammers it does not check logins, but only checks registrations and comments. 
It also repairs many bugs that I found in the Stop Spammers plugin and has many new methods for detecting spam.
<h3>Donate</h3>
Please buy one of my books and give it a good review. I worked hard on these books, and they are worth reading. 
See my books and contacts: https://linktr.ee/keithpgraham

Astounding Spam Prevention

Based on Stop Spammers, this lightweight spam stopper is still aggressive enough to stop 99% of the spammers and robots hitting your site. It is careful to never lock a webmaster out of WordPress. The options interface is slick and the logging is very very useful. 
I use it on 11 of my sites and I have my clients all using it.
Thanks to Will and all the effort he put in to make this plugin extremely useful while still being very very safe.

Works like a charm

It kills the spam

Got dozens of registrations after installing and activating all options. It made no difference what options were set. Uninstalled.

Made no difference to the spam

Very effective anti-spam plugin that eliminates comment spam, and registration spam. Combines many effective methods for identifying spammers and keep …

Stop Comment Spam vs Astounding Spam Prevention