PHP IMAP - Connection Failed

I have successfully setup an email server for myself using this DO tutorial for Postfix, Dovecot, MySQL, and RoundCube. I skipped spamassasin. Everything works fine, I can send and receive emails, and manage them through roundcube or my iphone.

But now I have spent 8 hours on this PHP problem, here’s the simplest I can reproduce it…

<?php
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

$mbox = imap_open("{localhost:143/imap}", "john@example.com", "johnspassword", OP_HALFOPEN);
?>

Gives the errors

Warning: imap_open(): Couldn't open stream {localhost:143/imap} in /var/www/example.com/public_html/test.php on line 6
Notice: Unknown: Connection failed to localhost,143: Connection refused (errflg=2) in Unknown on line 0

That is the error that shows for the php output. I can’t seem to find a log file with the same information. All I want is to connect to my emails.