SzMake

In English:
No spam in the <a href='https://wordpress.org/plugins/contact-form-7/' rel="ugc">Contact Form 7</a>.Add anti-spambot functionality to the CF7.
It blocks spam without using CAPTCHA,blocked by Invisible internal token-code with ajax.
This plugin blocks 100% of spam post in the author of the environment.
There is no modification of display the contact form.(The added field hidden)
(but the message which is posted by spammers manually via browser is not blocked by this plugin)
This method is the same as the <a href='https://wordpress.org/plugins/sz-comment-filter/' rel="ugc">Sz Comment Filter</a> which is released ahead.
In Japanese:
このプラグインは<a href='https://wordpress.org/plugins/contact-form-7/' rel="ugc">Contact Form 7</a>へのスパムbotからの投稿をブロックするプラグインです。
このプラグインでは、見えない入力欄を用意して投稿時にjavascriptでCAPTCHA入力に変わる固有の確認トークン入力処理をで行うことでスパムBotからの投稿をブロックします。
作者の環境では、今のところこのプラグインで100％スパムBOT投稿がブロックできています。
利用ユーザーのコメントフォームの見え方は変わりません。(追加される入力欄は非表示でユーザーから見えません)
(残念ながらこのプラグインではブラウザを介した手入力によるスパム投稿はブロックできません)
この対策手法は先にリリースしている <a href='https://wordpress.org/plugins/sz-comment-filter/' rel="ugc">Sz Comment Filter</a> と同じ方法です。
<a href="http://wp.szmake.net/contact-from-7-add-spam-bot-filter/" title="Documentation in Japanese" rel="nofollow ugc">日本語の詳細説明ページはこちら</a>
<h4>IMPORTANT NOTE</h4>
This plugin works with ContactForm7 3.6+,or later versions.
This plug-in is not related to the developer of the “Contact Form 7”.
(ja)このプラグインはContact Form 7 バージョン3.6以降との組み合わせで動作します。
(ja)このプラグインの作者はContact Form 7プラグイン開発元とは関係ありません。ご注意下さい。
<h4>Translators</h4>
<ul>
<li>Japanese (ja)</li>
</ul>
<h3>Contact</h3>
email to contact[at]szmake.net
twitter @sxmtz

Contact Form 7 Anti Spambot

No spam in the Contact Form 7.Add anti-spambot functionality to the CF7,it blocks spam without using CAPTCHA.

codetipi

Damn Spam WordPress Plugin
Damn Spam is a lightweight plugin to help clean up that darned spam. This plugin is highly opinionated and, once activated, will automatically send any comments that contain links in the comment body directly to the spam inbox. Granular settings for deeper control will be added over time.
If you’re tired of having to sift through hundreds of comments to find real ones without any links and manually send spammy ones to the spam inbox – then this is the plugin is for you.
<h3>Reporting Bugs</h3>
If you run into any issues, please let us know by <a href="https://github.com/codetipi/damn-spam/issues/new" rel="nofollow ugc">opening up a new issue here</a>.

Damn Spam

Damn Spam is a lightweight anti-spam plugin. Currently highly opinionated - it automatically sends any new comments with links to your spam inbox

Contact Form 7 Anti Spambot vs Damn Spam