Unable to send email from GoDaddy hosted php site - phpmailer

Question

I have tried the solutions from the top 10 stack overflow questions and other resources found online before posting my question here;
I have a php site that's hosted on GoDaddy that's trying to send emails to an Office365 (same defect presents when sending to my gmail though). When originally developed 3 years ago, it would send emails no problem, sometime last year it stopped sending emails.
The original code that used to work
$admin_email = "email#domain.com";
$email = $_REQUEST['email'];
$message = $_REQUEST['message'];
$message = 'FROM: ' . $email . "\r\n" . $message;
mail($admin_email, "New Message", $message, "From:" . $admin_email);
I also tried using PHPMailer with all manner of options.
These two don't error but I never get the email.
$mail = new PHPMailer;
$mail->Host = "relay-hosting.secureserver.net";
$mail->Port = 25;
$mail->SMTPDebug = 0;
$mail->SMTPSecure = "none";
$mail->SMTPAuth = false;
$mail->Username = "";
$mail->Password = "";
$mail->SMTPDebug = 0;
$mail = new PHPMailer;
$mail->isSMTP();
$mail->Host = 'localhost';
$mail->Port = 25;
$mail->ssl = false;
$mail->authentication = false;
And this one throws SMTP -> ERROR: Failed to connect to server
$mail = new PHPMailer;
$mail->SMTPDebug = 2;
$mail->IsSMTP();
$mail->Host = 'localhost';
$mail->SMTPAuth = false;
All are sent with
$mail->From = $from;
$mail->FromName = $admin_email;
$mail->AddAddress($email);
$mail->Subject = "New Message";
$mail->Body = $message;
$mail->IsHTML(true);
$mailresult = $mail->Send();
I have also made sure the domain has the following txt records
NETORGFT1413837.onmicrosoft.com
v=spf1 include:spf.protection.outlook.com -all
v=spf1 include:secureserver.net -all
Yes I checked junk/spam folders
The regular php mailer mail($to,$subject,$message,"From:email#address.com"); sends to gmail junk folder doesn't reach Office365 account

Answer 1

The regular php mailer mail($to,$subject,$message,"From:email#address.com"); sends to gmail junk folder doesn't reach Office365 account
I believe the reason this goes to your junk folder in Gmail is because emails sent via PHP's mail() function through GoDaddy are not authenticated. I also tried to utilize SPF records to resolve this, but it was unsuccessful.
Here's a workaround that you might be interested in if you have a Gmail account.
Requirements:
Gmail account, XAMPP or similar local web server, PHPMailer library
(tutorials on how to use XAMPP and PHPMailer are abundantly available online)
Instructions:
Go to "Settings" in your Gmail account. Under "Accounts and Import,"
add "youraccount#domainyouown.com" in the "Send Mail As" section.
In your PHP script (using the PHPMailer library), replace the credentials in the following lines of code with your Gmail credentials and the account you'd like to send from:
$mail->Username = 'username#gmail.com';
$mail->Password = 'yourpassword';
$mail->setFrom('youraccount#domainyouown.com', 'Your Name');
$mail->addReplyTo('youraccount#domainyouown.com', 'Your Name');
Added benefits of this method:
Emails are authenticated. I spent quite a while trying to achieve this via GoDaddy, to no avail. This removes the "possible spam" notification that is sometimes present with emails sent through hosting server relays...
Emails are sent faster. For whatever reason, the emails I sent via GoDaddy using PHP's mail() function took a few minutes to go through. Gmail takes seconds.
Copies of the emails you send actually show up in your Gmail "Sent" folder. This was also something that I could not achieve via GoDaddy, and I was told by customer support that this is a limitation of the service.