Fix WordPress wp_mail Return Path header, which is used for SPF checks, so that it matches From domain.

fix-mail-return-path.php

<?php
/*
Plugin Name: Email Return Path Fix
Author: Abdussamad Abdurrazzaq
Author URI: https://abdussamad.com/archives/567-Fixing-the-WordPress-Email-Return-Path-Header.html
*/
class email_return_path {
  	function __construct() {
		add_action( 'phpmailer_init', array( $this, 'fix' ) );    
  	}
 
	function fix( $phpmailer ) {
	  	$phpmailer->Sender = $phpmailer->From;
	}
}
 
new email_return_path();