Fumiki Takahashi

Hametuha INC.

This plugin enables you to send emails to each of your users. 
No more long to or BCCs.
<h4>Features</h4>
<ul>
<li>Use SMTP API to send emails. This affects all PHP Mailer in <code>wp_mail()</code> functions, 
so you can use this plugin with other mail-delivering plugins like WooCommerce and Form plugins.</li>
<li>User contact email.</li>
<li>HTML SendGrid email Template.</li>
<li>Override default email functions.</li>
<li>Marketing Email creator</li>
<li>Periodical Email(experimental)</li>
</ul>
<h4>Enter API Key</h4>
You need <a href="https://sendgrid.com/docs/Classroom/Send/How_Emails_Are_Sent/api_keys.html" rel="nofollow ugc">SendGrid API Key</a>.
For more details, go to hamail setting screen.

Hamail – Send Email via SendGrid

A WordPress plugin to send contact mail to your users via Sendgrid.

Surbma

CherryPick Studios

This plugin is created especially for Multisite Networks. You can define all variables in the wp-config.php file and it will be valid for all sites in a Multisite. So this is not for a site-by-site configuration plugin. You can install it on a single WordPress install also and it will work perfectly. But if you install it in a Multisite Network, you can only network activate it!
This plugin is working with all SMTP servers and services, like Mailgun, SendGrid, Mandrill, Amazon SES and others.
Required variables:
<ul>
<li><code>SURBMA_SMTP_HOST</code> – External SMTP server.</li>
<li><code>SURBMA_SMTP_USER</code> – User for the SMTP account.</li>
<li><code>SURBMA_SMTP_PASSWORD</code> – Password for the SMTP account.</li>
</ul>
Optional variables:
<ul>
<li><code>SURBMA_SMTP_PORT</code> – Port number for the SMTP server.</li>
<li><code>SURBMA_SMTP_SECURE</code> – Choose SSL or TLS, if necessary for your SMTP server.</li>
<li><code>SURBMA_SMTP_FROM</code> – From email address for all outgoing emails.</li>
<li><code>SURBMA_SMTP_FROMNAME</code> – From name for all outgoing emails.</li>
</ul>
Example configuration:
<pre><code> define('SURBMA_SMTP_HOST','smtp.mailgun.org');
 define('SURBMA_SMTP_USER','postmaster@surbma.com');
 define('SURBMA_SMTP_PASSWORD','bb2b************************4133');
</code></pre>
You can put these lines everywhere before the line, that says: “That’s It. Pencils down”
Do you want to contribute or help improving this plugin?
You can find it on GitHub: <a href="https://github.com/Surbma/surbma-smtp" rel="nofollow ugc">https://github.com/Surbma/surbma-smtp</a>
You can find my other plugins and projects on GitHub:
<a href="https://github.com/Surbma" rel="nofollow ugc">https://github.com/Surbma</a>
Please feel free to contribute, help or recommend any new features for my plugins, themes and other projects.
Do you want to know more about me?
Visit my webpage: <a href="http://surbma.com/" rel="nofollow ugc">Surbma.com</a>

Surbma | SMTP

External SMTP mail configuration via global variables in wp-config.php.

Hamail – Send Email via SendGrid vs Surbma | SMTP