Set reply-to header in emails to get around SMTP issues.

my_pmpro_wp_mail.php

/*
	Set reply-to header in emails to get around SMTP issues.

  I forget why I needed this, but I believe WP Manril or an SMTP app was using the incorrect reply to.
*/
function my_pmpro_wp_mail($args)
{	
	if(!empty($args['headers']))
	{
		foreach($args['headers'] as $header)
		{
			if(strpos($header, "From:") !== false)
			{
				$args['headers'][] = str_replace("From:", "Reply-To:", $header);
				return $args;
			}
		}
	}
	
	return $args;
}
add_filter('wp_mail', 'my_pmpro_wp_mail');