Joel

User Spam Remover is a plugin for WordPress that automatically removes spam user registrations and other old, never-used user accounts. It also blocks the notification e-mail that WordPress normally sends to the administrator whenever a new user registers (annoying when that registration is spam!) and logs it instead.
The plugin adds a configuration panel so that all of these options can be turned on or off, and it logs and fully backs up all user accounts that it deletes, so that you can restore them if you need to.
Features:
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Automatically deletes user registration spam and other orphaned, never-used accounts.
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Very simple, enable and go! Doesn’t interfere with the normal user registration process in any way. So, it doesn’t add captchas or activation or anything else — you’re free to use it alongside a plugin that does, if you like.
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Blocks notification e-mail that WordPress normally sends to the administrator every time a new user registers (instead, logs this event).
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Fully configurable, with grace period for new accounts and optional username whitelist.
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Fully logs all actions and backs up all user accounts that it deletes so that you can seamlessly restore them if you ever need to.
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Please see requirements and installation instructions below, or online <a href="https://wordpress.org/support/topic/official-installation-instructions-and-what-to-do-about-errors/" rel="ugc">in the WordPress support forum</a>.
For more information, please go to: <a href="https://lyncd.com/user-spam-remover/" rel="nofollow ugc">https://lyncd.com/user-spam-remover/</a>

User Spam Remover

Great way to clean a long running site of "junk" users.

Removed over 29k in minutes..

Effective

Does not work with many WordPress sites throwing a fatal error about mysqli.

Fatal PHP error about mysqli on activation

I had 31000 subscribers on a old (WP 4.4) website where I accidentially had the option "anyone can register" turned on.
This plugin did the job of deleting all those subscribers. I had to do it in batches as it "only" deletes 1000 subs at the time.

Thanks a lot to the developer as it has saved me a lot of hassle!!

It works!

Automatically removes spam user registrations and other old, unused user accounts. Blocks annoying e-mail to administrator after new registrations.

Ismail

Restrict User Registration Plugin allows you to restrict registration for custom usernames, email addresses and custom email service providers.
<h3>Features:</h3>
<li>Restrict specific usernames:Allows you to easily add custom usernames in the dashboard options panel ( users > restrict registration ). Once you set up these custom usernames, each time someone tries to register to your WordPress blog/site providing this targeted username, the registration process is getting bailed and the user gets an error message.</li>
<li>Restrict specific emails:You can add specific email addresses ( example me@example.com) and they will be automatically ignored and rejected from user registration process.</li>
<li>Restrict emails from specific domain: This one can also be an anti-spam tool. Before digging into details about this one, an email service provider is the website (domain name) that follows @ in the email address. An example is gmail.com from Google, you can add these service providers domains and they will be ignored and restricted as well. An example is adding outlook.com to ignore all registrations using an email address ending in @outlook.com ( that’s a secure one by the way, from Microsoft.)</li>
<li>Custom error messages:You can set up custom error messages so that the users trying to register and getting bailed will then know what the issue is and what to do for better experience.</li>
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If you liked the plugin, please consider rating it, leaving a review, and sharing with others.
You can use the plugin’s support section here for your support threads.
Please try to contact me through <a href="http://samelh.com" rel="nofollow ugc">my website</a> if ever you want to get in touch.
We have great upcoming plugin projects, <a href="http://go.samelh.com/newsletter" rel="nofollow ugc">join our mailing list</a> to get them first!

Restrict User Registration

Giving myself a review, I use this plugin to restrict some usernames from being registered with, and disallow some email service providers that are mostly recognized as spam by the available tools over the net.



Works perfect

Not working at all

Allows you to restrict registration for custom usernames, email addresses and custom email service providers

User Spam Remover vs Restrict User Registration