BaiatuLuTata

This plugin overrides the default WordPress email sending function with MailGuns’s Mail Send API.
Key Features:
<ul>
<li>Toggle Email Override for Mailgun on/off</li>
<li>Enter your Mailgun API key and domain</li>
<li>Customize the “From” email and name</li>
<li>Send a test email directly from the settings page</li>
<li>Clean and native WordPress admin UI</li>
</ul>
<h3>External Services</h3>
This plugin integrates with the <a href="https://www.mailgun.com/" rel="nofollow ugc">Mailgun</a> email delivery service to send outgoing emails via its API instead of the default <code>wp_mail()</code> function.
When enabled, the plugin communicates with the following Mailgun API endpoint: https://api.mailgun.net/v3/YOUR_DOMAIN/messages
Data sent to Mailgun includes: 
– Sender name and email 
– Recipient email(s) 
– Email subject 
– Message body (text or HTML) 
– Optional headers (Cc, Bcc)
The plugin requires a valid Mailgun API key and domain to function. These credentials are stored in your WordPress database and used only to authenticate API requests to Mailgun.
Privacy Notice: 
By using this plugin, you agree to Mailgun’s <a href="https://www.mailgun.com/terms/" rel="nofollow ugc">Terms of Service</a> and <a href="https://www.mailgun.com/privacy-policy/" rel="nofollow ugc">Privacy Policy</a>. Ensure your use of Mailgun complies with local privacy laws and your own data protection policies.

Email Override for Mailgun

Replaces WordPress wp_mail() with MailGun's API. Adds a settings page to manage API key, sender info, and test email functionality.

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.

Email Override for Mailgun vs Surbma | SMTP