TAKAHIRO

EmailZap is a simple and lightweight plugin that replaces WordPress’s default mail sending with SMTP. 
You can easily configure SMTP host, port, encryption method, authentication, username, and password from the admin settings page.
Passwords are encrypted using AES-256-CBC before being saved to the database, enhancing your site’s security.

EmailZap

A lightweight and secure plugin that switches your WordPress email sending to SMTP. Configure your SMTP server easily from the admin panel.

rajuru

SparkPost

The <a href="https://www.sparkpost.com/" rel="nofollow ugc">SparkPost</a> email delivery service offers best in class deliverability to ensure your mail hits the inbox, live analytics to review, track and optimize your email activities, as well as highest performance when you need it most: always.
When the SparkPost plugin is enabled, all outgoing email from your WordPress installation is sent through your SparkPost service. From within <a href="https://app.sparkpost.com/" rel="nofollow ugc">the SparkPost UI</a> or <a href="https://app.eu.sparkpost.com/" rel="nofollow ugc">SparkPost EU UI</a>, you can then watch your campaigns unfold live by tracking your engagement metrics, learn what your audience responds to and even integrate more deeply with your app using the SparkPost API.
Requirements 
– PHP 7.0 or later 
– WordPress 5.5 or later

Send all your email from WordPress through SparkPost, the most advanced email delivery service.

EmailZap vs SparkPost