phpmailer but without host - php

Question

Previously I have the mail() function in PHP to work with my site. Now we got a domain for the site ( nginx server ) and now the mail() just does not want to behave, always returns false. I have the PHP ini set up for mail() with the correct domain as
So...I turned to PHPMailer and it's still not working....
I get this error....
Could not instantiate mail function.
so my question is what is going wrong? I do not have a SMTP host... i want to use the local server as the mailing server as it was working before and I believe I have the right set up for that.
Was installed with composer.
This is my code:
require_once($_SERVER['DOCUMENT_ROOT']."/vendor/phpmailer/phpmailer/src/PHPMailer.php");
require_once($_SERVER['DOCUMENT_ROOT']."/vendor/phpmailer/phpmailer/src/SMTP.php");
require_once($_SERVER['DOCUMENT_ROOT']."/vendor/phpmailer/phpmailer/src/Exception.php");
$emailer = new PHPMailer\PHPMailer\PHPMailer();
$emailer->IsMail();
$emailer->SetFrom("noreply#my.domain");
$emailer->FromName = "My Domain";
$emailer->AddAddress($admin_data['email']);
$emailer->isHTML(false);
$emailer->Subject = "test";
$emailer->Body = " test "
if(!$emailer->send()){
give_error("Send Email Error: " . $emailer->ErrorInfo);
return false;
}

Answer 1

When looking to get under the hood of why your PHPMailer-driven email is failing to send, be sure to turn on PHPMailer's "SMTPDebug" option.
To do this, set the SMTPDebug property to "3" after instantiating your PHPMailer object. In your code, it would look like:
//Echo errors, server responses, client message, data, commands & connection status
$emailer->SMTPDebug = 3;
This will echo out all errors, server responses, and client messages that the email might be spilling out as it's trying to complete its sending. With this, you should be able to get a better handle on what might be causing your email to mis-fire or not send at all.
Even if you're try-catching errors currently, it won't capture the full breadth and depth of information without this option turned on.
Please remember, however, to turn this option off before pushing to production. Setting the SMTPDebug property back to 0 will ensure you're not leaking errors, or important server information to the end-user.
//Will disable all debugging.
$emailer->SMTPDebug = 0
You can find more information about the SMTPDebug property within the PHPMailer documentation, which is likely named "PHPMailer-master/docs/" within your codebase.

Answer 2

Follow the links to the troubleshooting guide. In order for the mail() function to work, you need a local mail server installed - I recommend postfix. It’s nothing to do with your code.
That said, while using a local mail server is a good choice, it’s both faster and safer to use SMTP to localhost than to use the mail function. See the PHPMailer docs for why that is.