SMTP.com

<a href="https://smtp.com" rel="nofollow ugc">SMTP.com</a> was the first company to provide email delivery at scale for customers unsatisfied with traditional sending methods. With over 22 years of email delivery success, SMTP.com is the trusted transactional and email relay provider for over 100,000 businesses worldwide. This WordPress integration for SMTP.com enables you to send and track your emails seamlessly.
Don’t worry about maintaining your email server or taking care of its IP reputation, forget about dealing with ISPs like Gmail, Yahoo or Microsoft in attempting to understand why your email isn’t reaching its destination. SMTP.com manages all this on your behalf. Simply create a SMTP.com account to <a href="https://registration.smtp.com/?afid=wpplugin" rel="nofollow ugc">get started</a> and set up this plugin. Although this plugin is free you will need a paid subscription with SMTP.com to send emails from your WordPress site.
You can send emails from your WordPress site using the SMTP.com API or the standard SMTP protocol. Our plugin will suggest the best way for you to send email even if your provider has restricted access to outbound internet ports. Either way, SMTP.com will still ensure your email gets delivered.
Another useful feature provided with our WordPress plugin is the ability to track your email delivery from within the plugin itself. See the results of your recent sends to ensure successful delivery or identify the reason why your particular email hasn’t been delivered.


Didn't work with the API key, but managed with the login information.


Good

SMTP.com is a powerful and reliable SMTP delivery service that enables you to send and track high volume emails effortlessly.

Scott Reilly

Configure SMTP mailing in WordPress, including support for sending email via SSL/TLS (such as Gmail).
This plugin is the official successor to the original SMTP plugin for WordPress (wpPHPMailer).
Use this plugin to customize the SMTP mailing system used by default by WordPress to handle outgoing emails. It offers you the ability to specify:
<ul>
<li>SMTP host name</li>
<li>SMTP port number</li>
<li>If SMTPAuth (authentication) should be used</li>
<li>SMTP username</li>
<li>SMTP password</li>
<li>If the SMTP connection needs to occur over ssl or tls</li>
</ul>
In addition, you can instead indicate that you wish to use Gmail to handle outgoing email, in which case the above settings are automatically configured to values appropriate for Gmail, though you’ll need to specify your Gmail email address (including the “@gmail.com”) and password.
Regardless of whether SMTP is enabled, the plugin provides you the ability to define the name and email of the ‘From:’ field for all outgoing emails.
A simple test button is also available that allows you to send a test email to yourself to check if sending email has been properly configured for your site.
Links: <a href="https://coffee2code.com/wp-plugins/configure-smtp/" rel="nofollow ugc">Plugin Homepage</a> | <a href="https://wordpress.org/plugins/configure-smtp/" rel="ugc">Plugin Directory Page</a> | <a href="https://github.com/coffee2code/configure-smtp/" rel="nofollow ugc">GitHub</a> | <a href="https://coffee2code.com" rel="nofollow ugc">Author Homepage</a>

Configure SMTP

does exactly what it says. Been working like a charm 

simple and sweet

Most of my users and customers ask me: why my mails are not being sent? Why some mails sent from my site do not arrives?

The problem are spam filters and things like this, so SMTP is a basic tool to operate a site or ecommerce.

I have used many plugin to do this task but none like this. This solves the problem in an easy and functional way.

Simple and functional way to configure SMTP settings in your WordPress

Configure SMTP mailing in WordPress, including support for sending email via SSL/TLS (such as Gmail).

SMTP.com vs Configure SMTP