SMTP — which stands for Simple Mail Transfer Protocol — is an internet standard for email transmission. This protocol is used for receiving and sending emails. Big mail services such as Gmail, Yahoo Mail!, and Outlook may use their own proprietary protocol, but they keep use SMTP when sending or receiving emails from outside their systems.
WordPress has no built-in SMTP feature. Instead, it uses a function called wp_mail for mail delivery. Most form builder plugins — Including Elementor’s form builder — make use of the wp_mail function to deliver the form submission if the action button is set to email. Some e-commerce plugins (including WooCommerce) also use the same function for shopping transactions such as notification or confirmation.
The wp_mail function itself depends on the send_mail function belongs to PHP to work. If this function (send_mail) is disabled, then the wp_mail function cannot work. As a result, your form submissions and shopping transactions are failed to send. In such a case, you can install and configure an SMTP plugin to add an SMTP functionality to your WordPress site. This way, the mail delivery job will be handled by the SMTP plugin instead of the wp_mail function.
In addition to form builder plugins and e-commerce plugins, some email marketing plugins, such as weMail and Newsletter, also require SMTP to work. That is why an SMTP plugin is crucial enough if you use your WordPress site for a business purpose.
6 best free SMTP WordPress plugins
Now you have understood the role of an SMTP plugin on WordPress. Here are 6 of the best SMTP plugins you can use for free.
1. Post SMTP
Post SMTP is one of the most popular SMTP plugins for WordPress that you can use for free, totally free. You can use this plugin to configure Gmail as an SMTP server for your WordPress site. You just need to connect your Gmail account with this plugin using an API key. Configuring Gmail to become an SMTP server on your WordPress site is relatively easy with Post SMTP as it comes with a helpful configuration wizard. In addition to Gmail, Post SMTP also supports other SMTP services such as Mandrill, SendGrid, and Mailgun. If you use Google Chrome, the developer of this plugin also offers a Chrome extension to notify you over failed email delivery.
2. WP Mail SMTP
Do you use WPForms? If yes then WP Mail SMTP is a perfect plugin for you. This SMTP plugin is developed by WPForms. Unlike Post SMTP which is released as a free plugin, WP Mail SMTP — just like WPForms — is released as a freemium plugin. The free version allows you to configure Gmail as an SMTP server on your WordPress site. The free version also supports SendGrid, Sendinblue, and Mailgun. If you use SMTP services like Amazon SES, Outlook, Office 365, Microsoft SMTP, you need to use the pro version. Other features offered by the pro version of WP Mail SMTP include mail logging and notification management.
3. SMTP Mailer
SMTP Mailer is a great plugin if you have your own SMTP server and want to use it on your WordPress site. You just need to enter the SMTP host, SMTP login, and SMTP port. This plugin will do the rest.
4. Gmail SMTP
Gmail SMTP is an SMTP plugin developed by the same developer as the SMTP Mailer above. The difference, this plugin is designed specifically for Gmail. It is a great fit if you have no SMTP server and want to use Gmail as the SMTP server on your WordPress instead. Same as Post SMTP and WP Mail SMTP, you will need a Gmail API key to use this plugin.
5. WP Mail Bank
WP Mail Bank has one thing in common as WP Mail SMTP. This plugin is also released as a freemium plugin with the free version allows you to configure Gmail as the SMTP server on your WordPress site. If you have your own SMTP server, WP Mail Bank also allows you to use it on your WordPress site.
Popular SMTP services such as SendGrid and Mailgun are also supported by WP Mail Bank. However, you need to use the pro version to use it on your WordPress. The pro version comes with a report and notification feature. WP Mail Bank itself is easy enough to use as it offers a helpful configuration wizard.
6. Easy WP SMTP
Easy WP SMTP is a suited plugin if you have your own SMTP server and want to use it on your WordPress site. Just like SMTP Mailer, you just need to provide the SMTP host, SMTP login, and SMTP port of your SMTP server to use it on your WordPress site. In addition to using your own SMTP server, Easy WP SMTP also allows you to configure Gmail, Yahoo Mail, and Hotmail to become an STMP server on your WordPress site.