Jure

Plugin will automatically check all the inputs with “email” type and suggest a correction to the visitor in case of a typo. 
Example: “john.doe@gmal.com” instead of “john.doe@gmail.com”.
This is especially useful when sending transactional emails back to the customer after placing an order, submitting a contact form, etc.
Sending emails to the non-existent addresses will result in so called “bounces” which will decrease reputation of your sending IP address. 
Your server’s IP address might get blacklisted and your customers will no longer receive emails from you.
Plugin is using “Mailcheck.js” library: 
https://github.com/mailcheck/mailcheck/

Email Address Validator

By using this plugin, website looks and feels more professional by suggesting correct email address in case of a typo.

Website feels more professional

This plugin is great. Now I have fewer invalid emails on my orders!

Amazing plugin

Check email address inputs for common typos and fix them with only one click. Easily define custom checks.

ortox

With this plugin visitors will be able to report typos or mistakes seen on your websites. 
Select the error and click Ctrl+Enter. Inform your visitors about this ability with widget or shortcode.
С помощью данного плагина посетители смогут сообщить об опечатках или ошибках, замеченных на ваших сайтах.
Для того, чтобы отправить сообщение об ошибке, необходимо выделить текст на странице сайта, где замечена ошибка, и нажать сочетание клавиш Ctrl+Enter или специальную ссылку. Появится диалоговое окно, в котором пользователь сможет написать комментарий и отправить сообщение об ошибке.
http://support.prihod.ru/docs/konfiguraciya-sajta/soobshhit-ob-opechatke/
Requirements: WordPress 3.3+, PHP5 and higher

Report an error

With this plugin visitors will be able to report typos or mistakes seen on your websites.

Email Address Validator vs Report an error