EverPress

Verifies your subscribers email addresses. Read more on the <a href="https://kb.mailster.co/reduce-false-signups-with-email-verification/?utm_campaign=wporg&utm_source=Email+Verify+for+Mailster&utm_medium=readme" rel="nofollow ugc">Mailster Knowledge base</a>
This plugin is no longer needed since Mailster 3.0!
<h3>Additional Info</h3>
<blockquote>
This Plugin requires <a href="https://mailster.co/?utm_campaign=wporg&utm_source=Email+Verify+for+Mailster&utm_medium=readme" rel="nofollow ugc">Mailster Newsletter Plugin for WordPress</a>
</blockquote>

Mailster Email Verify

The plugin will reject the email address if there is no such domain, but the SMTP ping to see whether the actual email address exists or not doesn't work.
Without this, it's not really useful.

MX checking works, SMTP doesn't

Verifies your subscribers email addresses. Read more on the Mailster Knowledge base

Xaver

Mailster Newsletter Plugin

See who opens your newsletter campaigns in real time.
<blockquote>
This Plugin requires <a href="https://mailster.co/?utm_campaign=wporg&utm_source=wordpress.org&utm_medium=readme&utm_term=Mailster+Live" rel="nofollow ugc">Mailster Newsletter Plugin for WordPress</a>
</blockquote>

Mailster Live

See who opens your newsletter campaigns in real time.

Mailster Email Verify vs Mailster Live