Issue with sending email using PHP mail(). Suspect a link between PHP and Mercury Mail is the issue

Question

I am trying to send email from my local windows computer for testing changes to my live website.

I have: XAMPP stack running (ver 3.2.3) PHP Version 7.3.4 Mercury Mail version: Mercury/32, v4.62,

I have configured Mercury Mail and can send test emails from within it.

I have changed PHP,ini as shown below:

[mail function] SMTP=localhost smtp_port=25 sendmail_from=postmaster@localhost sendmail_path = "C:\xampp\sendmail\sendmail.exe" -t"

sendmail.ini

smtp_server=localhost smtp_port=25 smtp_ssl=auto

I have a little PHP file for testing

if (mail('myemail@mydomain.ca','Test Email','This is a test')) {
   echo('success');
}

else {
echo ('failed'); }

When I run this in the browser it returns success but I do not recieve the email.