Itthinx Mail Queue


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Mail Queue & SMTP for WordPress

Improve the user experience on your WordPress site through the way emails are handled!

The Itthinx Mail Queue plugin for WordPress features a fully automated email queue that substantially improves the way emails are sent out from your site:

  • Improves the user experience for form submissions, don’t make your visitors wait!
  • Eliminates delays during comment submissions and optimizes large amounts of notifications.
  • Balances the strain that emails put on your site and servers.
  • Prioritizes emails based on whether they are sent by the WordPress core, a plugin or the theme. Allows to send emails immediately, use the queue or to block them.
  • Avoids bounced and rejected emails by using SMTP to send them.
  • Fixes common issues when sending email from WordPress.


Fixing common Email Issues

It is very common to see issues when you rely on the standard process to send out emails via WordPress. Emails are often rejected or not sent at all. This can include important emails such as order confirmations with WooCommerce, notifications on new user registrations, blog post and comment notifications that your subscribers should receive. Many of these cases result in unwelcome results ranging from a reduced blog audience to serious issues like refund requests because your customers have not received your order and payment confirmation. The Itthinx Mail Queue plugin helps to eliminate these issues.

  • E-Commerce – Assure that order and payment confirmations are sent with the highest priority and don’t end up in your customer’s spam folder.
  • Contact Forms – Make sure that you receive notifications, that those who try to contact you can enjoy a smooth form submission experience and that they receive appropriate confirmations.
  • First things first – Prioritize urgent and important emails over lower priority notifications, while making sure that all emails are sent out in due time.
  • Avoid being flagged as spam – Are you using a shared server environment to host your site? Shared servers are often blacklisted because some of your neighbors abuse the server to send out their junk emails. Instead of risking your emails being flagged as spam, too, use a reputable and independent SMTP server to send out emails.
  • Avoid congestion, delays and exceeded rate limits – When you send out large amounts of emails via your site, it can happen that they are delayed or rejected because you exceed rate limits. Internet Service Providers, on both the sending and receiving end, may enforce rate limits according to the service contract, trust level and reputation of the IPs involved. An email queue helps to keep the number of emails that are sent out within reasonable and accepted limits.


The Mail Queue gathers emails that are sent on a deferred schedule. It allows to adjust the frequency and the number of emails that are sent out periodically.

Determine the average throughput of the email queue and limit the number of emails sent per hour.

  • Hosted Email : Third-party email providers like Gmail, MailChimp / Mandrill, MailPoet, Mailgun, … usually enforce certain limits to the amount of emails that you can send through their facilities. You can adjust the values here to assure that when your site tries to send emails, they will not be rejected by your email provider because you exceed those limits.
  • Self-hosted Email : If you are using your own email server, this is useful to adjust the emails sent in accordance with the resources that are allocated to your email server.
  • Blogs with many Subscribers : A particularly useful case for the application of the Mail Queue is when blog post or comment notifications are sent out to hundreds or thousands of subscribers at a time. WordPress with many common popular plugins intends to notify all those subscribers at once, failing to manage these large amounts of emails being sent out appropriately. Essentially, each time you publish a new blog post that should reach a large audience or when a new comment is approved on a popular post, your site will try to send out emails to all those people and very likely fail, or leave you waiting in despair, as it exceeds sensible limits. The Mail Queue postpones all those emails and sends them out gradually, providing a reliable way to have all those subscribers notified in due time.

The queue’s parameters determine how many emails are sent and for how long the data is kept in the queue after they have been sent. The system sends out a batch of emails per cycle. You determine the time between each cycle in seconds and how many emails are sent per cycle.



Decide how emails sent from your site are treated, based on which component or Sender is originating them:

  • WordPress Core – Choose how emails are sent from the WordPress core
  • Plugins – Control how emails are sent by plugins in general or for a specific plugin
  • Theme – Decide how emails are sent that originate from the active theme, for example by its built-in contact forms and other functions

For each component, you can specify an Action and a Priority. The action determines how an email sent by the component is handled while the priority dictates which ones are handled first. Actions include the option to send emails immediately, add them to the queue to be sent on their turn and you can even block outgoing emails for a component.


Avoid problems with your WordPress site not sending emails. With SMTP enabled and configured, emails are sent out from your site using your SMTP email server instead of your web server.


  • WordPress 5.6 or higher.
  • PHP 5.6 or higher.
  • MySQL 5.6 or higher.
  • Working WP-Cron – Queue processing requires that WordPress scheduled tasks are executed
  • No existing wp_mail() override. You must not use another plugin or a customized implementation that overrides the standard WordPress wp_mail() function as this will not be compatible and interfere with this plugin’s correct operation. If you have such a plugin or customization currently in place, disable and remove it to use Itthinx Mail Queue instead.

Additional information


Single Site, Up to 25 Sites, Up to 5 Sites

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