Site contact form not working -- using Bluehost and Gsuite

Question

I know this is a question that's been asked a lot, but I've been through the steps in the other threads and it hasn't seem to help. Been struggling with this for a week and would really appreciate help!

Here are the key pieces:

1. mail() returns true
2. The emails are not arriving
3. I'm sending from [email protected] which is setup on both Bluehost and Gsuite with matching passwords
4. Bluehost is adamant all their SMTP settings/MX records are correct
5. GSuite email record logs show no emails in the queue from my site (and they're adamant it's Bluehost's fault)
6. error_reporting(E_ALL) shows nothing
7. HTML posts all variables correctly to PHP
8. Both email accounts (sending and received) can both send and receive emails

I think the SMTP settings may be wrong, but Bluehost support is saying they can't directly change these. Details below...

PHP CODE

<?php   
  //ERROR REPORTING 
    //error_reporting(E_ALL);
    //ini_set('display_errors', '1');

  //POST VALUES
    $name=$_POST['name'];
    $business=$_POST['business_name'];
    $email=$_POST['email_address'];

    $subject='[CONTACT PAGE] '
        .strtoupper($_POST['subject'])
        .' request from $name'
        .' ($business)';
    // The above variables confirmed to all POST

    $message = '[name] '.$name.'\n'
            .'[business] '.$business.'\n'
            .'[email] '.$email.'\n\n'
            .'[subject] '.$subject.'\n'
            .$_POST['message'];     

    $to = '[email protected]';
    $from = '[email protected]'; //Email set up on Gsuite

    $headers  = 'MIME-Version: 1.0' . "\r\n";
    $headers .= "Content-type: text/html; charset=iso-8859-1\r\n";
    $headers .= 'From: '.$from;
    if (mail($to, $subject, $message, $headers)) {
        $location='Location: ./contact-thanks.php';
    } else {
        $location='Location: ./error';
    }

    header($location);
    die();
?>

MX RECORDS

priority    host record points to   ttl action
1   @   aspmx.l.google.com  14400   edit delete
5   @   alt1.aspmx.l.google.com 14400   edit delete
5   @   alt2.aspmx.l.google.com 14400   edit delete
10  @   alt3.aspmx.l.google.com 14400   edit delete
10  @   alt4.aspmx.l.google.com 14400   edit delete

BLUEHOST EMAIL CONFIGURATION

Email Settings

Mail Server Username: [email protected]

Standard (without SSL)

Incoming Mail Server: mail.mysite.com
Supported Ports: 143 (IMAP), 110 (POP3)
Outgoing Mail Server: mail.mysite.com
Supported Port: 26 (server requires authentication)
Private (with SSL)

Incoming Mail Server: mail.mysite.com
Supported Ports: 993 (IMAP), 995 (POP3)
Outgoing Mail Server: mail.mysite.com (SSL)
Supported Port: 465 (server requires authentication)
Supported Incoming Mail Protocols: POP3, IMAP
Supported Outgoing Mail Protocols: SMTP