diff --git a/includes/bootstrap.php b/includes/bootstrap.php
index b443478..390fbaf 100644
--- a/includes/bootstrap.php
+++ b/includes/bootstrap.php
@@ -22,6 +22,67 @@ function wp_mail( $to, $subject, $message, $headers = '', $attachments = [] ) {
 		return $phpmailer->wpmail($to, $subject, $message, $headers, $attachments);
 	}
 
+} else {
+	// Disable whatever plugin has added its own wp_mail function.
+
+	require_once( ABSPATH . 'wp-admin/includes/plugin.php' );
+
+	/**
+	 * Given a filename, figure out what plugin it is from.
+	 *
+	 * @param string $filename The file path we're trying to determine the plugin for.
+	 *
+	 * @return string|null The plugin file name, e.g. "disable-emails/disable-emails.php".
+	 */
+	 $get_plugin_file_from_path = function ( $filename ) {
+
+		// If the file is outside the plugins dir, whats's up? MU plugins?
+		if ( ! stristr( $filename, WP_PLUGIN_DIR ) ) {
+			return null;
+		}
+
+		// Remove the path/to/wp-content/plugins.
+		$plugin_file = trim( substr( $filename, strlen( realpath( WP_PLUGIN_DIR ) ) ), DIRECTORY_SEPARATOR );
+
+		$plugins = get_plugins();
+
+		// This will only work if wp_mail is defined in the plugin's main file.
+		if ( array_key_exists( $plugin_file, $plugins ) ) {
+
+			return $plugin_file;
+		}
+
+		// Get the first part of the file path to the first /.
+		$plugin_slug = substr( $plugin_file, 0, strpos( $plugin_file, DIRECTORY_SEPARATOR ) );
+
+		// If the file is in the plugin's folder.
+		foreach ( $plugins as $plugin_file_name => $plugin ) {
+
+			if ( stristr( $plugin_file_name, $plugin_slug ) ) {
+				return $plugin_file_name;
+			}
+		}
+
+		return null;
+	};
+
+	$wp_mail_reflector = new \ReflectionFunction( 'wp_mail' );
+	$wp_mail_filename  = $wp_mail_reflector->getFileName();
+
+	$built_in_wp_mail_filename = 'wp-includes/pluggable.php';
+
+	// If wp_mail has been overridden.
+	if ( substr( $wp_mail_filename, - 1 * strlen( $built_in_wp_mail_filename ) ) !== $built_in_wp_mail_filename ) {
+
+		$plugin_file = $get_plugin_file_from_path( $wp_mail_filename );
+
+		if ( null !== $plugin_file ) {
+
+			deactivate_plugins( $plugin_file );
+
+		}
+	}
+
 }
 
 /**
diff --git a/readme.txt b/readme.txt
index 525ba35..ea9a8c4 100644
--- a/readme.txt
+++ b/readme.txt
@@ -1,5 +1,5 @@
 # Disable Emails
-Contributors: webaware
+Contributors: webaware, BrianHenryIE
 Plugin Name: Disable Emails
 Plugin URI: https://shop.webaware.com.au/downloads/disable-emails/
 Author URI: https://shop.webaware.com.au/