Mailtrap filter for WordPress

mailtrap-filter.php

/**
 * Routes all email from WP installation to specific Mailtrap
 * account inbox.
 * 
 * All you need to do is change the "Username" and "Password"
 * settings to the appropriate box in Mailtrap.  Then all
 * mail **should** be routed to that box.  Exceptions would
 * be other functionality that overwrite the wp_mail() functions
 * and may not use this filter, or other filters that change
 * this behavior after we set it, or millions of other things.
 *
 * @param object $phpmailer - PHPMailer object (by reference)
 */
function use_mailtrap($phpmailer) {
	$phpmailer->IsSMTP();
	$phpmailer->SMTPAuth   = true;
	$phpmailer->Host       = "mailtrap.io";
	$phpmailer->Port       = 2525;
	$phpmailer->Username   = "";
	$phpmailer->Password   = "";
}
add_action( 'phpmailer_init', 'use_mailtrap' );

I've wrapped it into a plugin:
https://wordpress.org/plugins/mailtrap-for-wp/