Benaceur

This plugin allows you to Restrict a particular or certain username, email addresses or symbols, 
or email from specific domain names in the form registration when registering for your site 
and you can allow to use a certain language (arabic cyrillic latin …) 
or all languages and characters and symbols, you can also control and modify all errors messages 
and allow certain characters (Symbols and characters accented as é û), 
and allowing you to change the author slug (defaults to the username of the author), 
and you can control and adjust all settings from the plugin settings page in admin Panel.
<h4>and here is all plugin settings in admin Panel:</h4>
<ul>
<li>enable/disable the plugin</li>
<li>disallow to use the spaces in username</li>
<li>disallow to use only numbers in username</li>
<li>disallow all characters (Symbols) in username</li>
<li>disallow characters (Symbols) permitted by wordpress in username: @ – . _</li>
<li>allow certain characters (Symbols and characters accented as é û)</li>
<li>restrict certain email addresses</li>
<li>restrict certain username</li>
<li>restrict certain domain names for example: yournamesite@com</li>
<li>No/yes uppercase in username</li>
<li>Compatible with single site, network (multi-site), buddypress and buddyboss.</li>
<li>The possibility to:</li>
<li>choose language (characters) in username (arabic cyrillic latin …) or all languages</li>
<li>remove all settings and data of the plugin from database when the plugin is disabled</li>
<li>reset default settings</li>
<li>control and modify all errors messages</li>
<li>restrict any name contains a part of word (partial matching)</li>
<li>prevent the use of email in the username</li>
<li>prevent the use of numbers more than letters and symbols in the user name.</li>
<li>allowing you to change the author slug</li>
<li>Author Slug Structure</li>
<li>Update of the author’s slug for all users</li>
<li>Limit the number of users to update (in batches) with every click, if your database is big</li>
<li>Update or convert only names (author slug) not latin</li>
<li>remove name field in buddypress.</li>
<li>hide or change message (Must be at least 4 characters, letters and numbers only.) of multisite.</li>
<li>add an notice or text in registration form.</li>
<li>etc…</li>
</ul>
<h4>TRANSLATED IN FOLLOWING LANGUAGES:</h4>
<ul>
<li>Arabic</li>
<li>English</li>
</ul>
<h4>Direct support page:</h4>
https://benaceur-php.com/?p=2268

Restrict Usernames Emails Characters

Restrict the usernames, email addresses, characters and symbols or email from specific domain names or language in registration ...

Brandon Allen

This plugin allows full control of your user permalinks, allowing you to change both the author base (the ‘/author/’ portion of the author URLs), and the author slug (defaults to the username of the author). You can set the author base globally, or you can set it to be user-specific based on a user’s role. You now have the power to craft the perfect URL structure for you Author pages.
WordPress default structure http://example.com/author/username/.
Edit Author Slug allows for http://example.com/ninja/master-ninja/.
Using a role-based author base would allow for http://example.com/ida/master-splinter/ (for an Administrator Role), or http://example.com/koga/leonardo/ (for a Subscriber Role).
Development of this plugin takes place on <a href="https://github.com/thebrandonallen/edit-author-slug/" title="Edit Author Slug on Github" rel="nofollow ugc">GitHub</a>. Pull requests are always welcome!
Translations should be submitted to <a href="https://translate.wordpress.org/projects/wp-plugins/edit-author-slug" rel="nofollow ugc">Translate WordPress</a>.

Edit Author Slug

Allows an admin (or capable user) to edit the author slug of a user, and change the author base.

Restrict Usernames Emails Characters vs Edit Author Slug