How to use pre_wp_mail filter in WordPress

pre_wp_mail filter

Returning a non-null value will short-circuit wp_mail(), returning that value instead. A boolean return value should be used to indicate whether the email was successfully sent.

To use pre_wp_mail filter, first you have to register it using add_filter. You can write this code into the functions.php of your activated theme or in a custom WordPress Plugin.

We at WePlugins always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

In the below live example, we have defined a function modify_pre_wp_mail_defaults which takes 2 parameters and we registered using add_filter. The first parameter pre_wp_mail is the name of the hook, the second parameter modify_pre_wp_mail_defaults is the name of the function which needs to be called, the third parameter is the priority of calling the hook if the same hook is used multiple times, and the last parameter is the number of arguments (if any) to be passed in the registered function.

Sometime, you have to remove a registered hook so you can use remove_filter to remove pre_wp_mail filter.

Parameters

Below are the 2 parameters required to use this hook.

• $return : (null|bool) Short-circuit return value.
• $atts : (array) Array of the wp_mail() arguments.
  • ‘to’ (string|string[]) Array or comma-separated list of email addresses to send the message.
  • ‘subject’ (string) Email subject.
  • ‘message’ (string) Message contents.
  • ‘headers’ (string|string[]) Additional headers.
  • ‘attachments’ (string|string[]) Paths to files to attach.

Live Example

Below is an example of how you can use this hook.

Example 1: Basic Usage

In this example, we simply modify the $return variable based on our requirements.

    function weplugins_modify_pre_wp_mail_defaults($return, $atts) {
        // Update the $return variable according to your website requirements.
        return $return;
    }
    // add the filter
    add_filter( "pre_wp_mail", "weplugins_modify_pre_wp_mail_defaults", 10, 2 );
    

Example 2: Condition Based Modification

Here, we modify the $return variable conditionally based on the subject of the email.

    function weplugins_condition_based_pre_wp_mail_defaults($return, $atts) {
        if (strpos($atts['subject'], 'Important') !== false) {
            $return = true; // Short-circuit the wp_mail if the subject contains 'Important'
        }
        return $return;
    }
    // add the filter
    add_filter( "pre_wp_mail", "weplugins_condition_based_pre_wp_mail_defaults", 10, 2 );
    

Example 3: Removing the Hook

To remove a hook callback, use the example below. Make sure to provide the same callback function name, priority, and number of arguments while removing the hook callback.

    remove_filter( "pre_wp_mail", "weplugins_modify_pre_wp_mail_defaults", 10, 2 );
    

Contact Us

If you’re having any trouble using this hook or need customization, please contact us.