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

hildende

Birmania

This plugin adds emails to a mailing queue instead of sending immediately. This speeds up sending forms for the website visitor and lowers the server load. 
Emails are stored as files which are deleted after emails are sent.
You can send all outgoing emails via an SMTP server or (the WordPress standard) PHP function <a href="http://php.net/manual/en/function.mail.php" rel="nofollow ugc">mail</a>, and either use <a href="https://codex.wordpress.org/Function_Reference/wp_cron" rel="nofollow ugc">wp_cron</a> or a cronjob (if your server/hoster supports this) to process the queue.
Plugin requires PHP 5.4 or above.
Tools:
<ul>
<li>You can send test mails to test your setup.</li>
<li>You can process the mailing queue manually instead of waiting for cronjob.</li>
</ul>
Supervisors: 
* You can display basic informations about mail processing performances 
* You can display the mailing queue in the backend to see emails that will be sent with next processing. 
* You can display the invalid mails and delete or retry them. 
* You can display the sent mails and delete them.
Coming soon:
<ul>
<li>Storing mailing data in database instead of files.</li>
<li>Using plugin for SMTP mails without using mailing queue.</li>
</ul>
Feel free to suggest features or send feedback in the <a href="https://wordpress.org/support/plugin/smtp-mailing-queue" rel="ugc">support section</a>, via <a href="mailto:antoine.brultet@gmail.com" rel="nofollow ugc">email</a> or by creating a pull request on <a href="https://github.com/Birmania/smtp-mailing-queue" rel="nofollow ugc">github</a>.

SMTP Mailing Queue

Add emails to a mailing queue instead of sending immediately to speed up sending forms for the website visitor and lower server load.

Simple SMTP Mailer vs SMTP Mailing Queue