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.

Scribit

Proofreading plugin allows you to improve the quality of your posts, pages and all your WordPress website. 
It gives you the possibility to check the correction of the texts inserted into posts, pages and drafts in less than a second!
Press the “Analyze” button and you will have a list of all found errors. 
The plugin allows to recognize different types of text errors (thanks to Languagetool.org). Here some examples of error types: 
* Typos 
* Punctuation 
* Typography 
* Commonly Confused Words 
* Nonstandard phrases 
* Semantic 
* Grammar 
* Redundant Phrases
Proofreading plugin supports a lot of languages. For example: 
* English 
* Spanish 
* German 
* Italian 
* Japanese 
* French 
* Portuguese 
* Russian 
* and so on…
For every language, in the settings page, you can customize which are the error categories you are interesting, hiding the others.

Proofreading

I think it is very useful inside Wordpress world. All site must have it to avoid common text errors.
It does not take up much space in the backend Wordpress console so it can always be left activated.

P.S: I'm the autor of the plugin.

Very useful

Proofreading checks texts on every content of your WordPress site. You can proofread in 30 different languages and get tips to improve your writings.

Email Address Validator vs Proofreading