Josh Mckibbin

The <a href="https://kibb.in/ssmtp" rel="nofollow ugc">Simple SMTP Mailer</a> plugin allows you to easily configure WordPress to use SMTP instead of the PHP mail function.
This should only really be used in a development environment.
<h3>Simple SMTP Mailer Settings</h3>
<ul>
<li>Host: The mail server (Defaults to smtp.gmail.com)</li>
<li>Username: The username used for connecting to the SMTP server</li>
<li>Password: The password used for connecting to the SMTP server</li>
<li>Port: The port to use when sending an email (587, 465 or 25. Defaults to 587)</li>
<li>Security: The type of encryption security to use when sending an email (TLS or SSL. Defaults to TLS)</li>
<li>Debug: Enable debugging</li>
</ul>
All settings can be overridden by assigning array values to the SSMTP_MAILER constant in wp-config.php. This is useful for automating local deployment.
<pre><code>define(
 'SSMTP_MAILER',
 array(
 'host' => emailhost.com,
 'username' => username,
 'password' => password,
 'port' => 25,
 'security' => 'SSL'
 )
);
</code></pre>

Simple SMTP Mailer

Simplifies local development by configuring WordPress to use SMTP instead of the PHP mail() function

WonderPlugin

Display wp_mail Error Messages
Many plugins use the WordPress function <a href="https://developer.wordpress.org/reference/functions/wp_mail/" rel="nofollow ugc">wp_mail</a> to send emails. When an error happens, it’s hard to locate the problem. This plugin will catch the wp_mail error messages and display them.
Features
<ul>
<li>Easy to use</li>
<li>Automatically clear the log when it exceeds the defined maximum length limit.</li>
</ul>
How to Use
After the plugin is installed and activated, in the WordPress backend, goto the left menu WP Error Messages -> Show Errors.

Display wp_mail Error Messages

I just found this plugin and it has been very helpful with debugging. Thank you for this!

Simple SMTP Mailer vs Display wp_mail Error Messages