Martin Lormes

If a comment is held for moderation an email message is sent to the comment author with a link to verify the comment author’s email address. When the comment author clicks on that link the comment gets approved immediately. This makes discussions more lively as users don’t have to wait for the blog admin to approve the comment.
Blog owners may also choose to hold the comments in the moderation queue even after successful verification. The verification status is shown in the comment lists in the admin.
If an author has a previously approved comment and his comments gets approved automatically according to the ‘comment_whitelist’ option in WordPress no email is sent.
If a comment is classified as spam by Akismet or another anti-spam plugin no email is sent.
This plugin uses the <code>commentmeta</code> table and thus requires WordPress 2.9
PHP5 strongly recommended

Comment E-Mail Verification

Wish it supported embedded html in the verification email. One note. You must have Settings -> Discussion -> Comment must be manually approved checked in order for it to work. Once I figured that out, it works just fine.

Still works

If a comment is held for moderation an email message is sent to the comment author with a link to verify the comment author's email address.

Amin Abdolrezapoor

Dornaweb

Send Email verification links on WordPress
This plugin sends verification emails to newly registered wordpress users and asks them to verify their email address.
<h3>Adding your own localized email templates</h3>
The email templates are located under <code>tpl/emails</code> directory, and the file for verification email is called <code>verify.php</code> which is the default template for <code>english</code> language 
however you can add your own language-specific template file by duplicating <code>verify.php</code> and renaming it to <code>verify-LOCALE_CODE.php</code>
for example for Portuguese ( Brazil ) you can add a file named <code>verify-pt_BR.php</code> ( you can get your wordpress installation locale code with <a href="https://developer.wordpress.org/reference/functions/get_locale/" rel="nofollow ugc">get_locale()</a> )
There are also <code>dw_verify_email_template_path</code> and <code>dw_verify_email_template_args</code> filters available if you want to make modifications from your theme\’s <code>functions.php</code>
<h3>3rd-party scripts included</h3>
<a href="https://github.com/anthonybudd/WP_Mail" rel="nofollow ugc">WP_MAIL</a> ( for sending templated emails )

Email verification on signups

Simple and handy plugin

Send verification links to newly registered users and ask them to confirm their email address to activate their account.

Comment E-Mail Verification vs Email verification on signups