SMTP = smtp.example.com
smtp_port = 25
username = info@example.com
password = yourmailpassord
sendmail_from = info@example.com

smtp_server=smtp.gmail.com
smtp_port=465
auth_username=user@gmail.com
auth_password=your_password

[mail function]
; For Win32 only.
SMTP = mail.yourserver.com
smtp_port = 25
auth_username = smtp-username
auth_password = smtp-password
sendmail_from = you@yourserver.com

<?php
    $message = "test message body";
    $result = mail('recipient@some-domain.com', 'message subject', $message);
    echo "result: $result";
?>

#Relay config
relayhost = smtp.server.net
smtp_use_tls=yes
smtp_sasl_auth_enable=yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/postfix/cacert.pem
smtp_sasl_security_options = noanonymous

smtp.server.net username:password

composer require phpmailer/phpmailer

# use namespace
use PHPMailerPHPMailerPHPMailer;

# require php mailer
require_once "../vendor/autoload.php";

//PHPMailer Object
$mail = new PHPMailer;

//From email address and name
$mail->From = "from@yourdomain.com";
$mail->FromName = "Full Name";

//To address and name
$mail->addAddress("recepient1@example.com", "Recepient Name");
$mail->addAddress("recepient1@example.com"); //Recipient name is optional

//Address to which recipient will reply
$mail->addReplyTo("reply@yourdomain.com", "Reply");

//CC and BCC
$mail->addCC("cc@example.com");
$mail->addBCC("bcc@example.com");

//Send HTML or Plain Text email
$mail->isHTML(true);

$mail->Subject = "Subject Text";
$mail->Body = "<i>Mail body in HTML</i>";
$mail->AltBody = "This is the plain text version of the email content";

if(!$mail->send())
{
    echo "Mailer Error: " . $mail->ErrorInfo;
}
else
{
    echo "Message has been sent successfully";
}