How to run mail function only once? - php

Question

I want to send mail (only once) using php when $cstt == 10. I want to prevent sending mail on every time I refresh the page. here is my code
if ($cstt == 10) {
echo "Great";
// SENDING EMAIL
$to = "user#example.com";
$subject = "$tracking_id_user is in transit.";
$message =' Hi user, Simple html message. Best Regards!';
$headers = "MIME-Version: 1.0" . "\r\n";
$headers .= "Content-type:text/html;charset=UTF-8" . "\r\n";
$headers .= 'From: Company <info#company.com>' . "\r\n";
if(mail($to,$subject,$message,$headers)){
echo "mail send";
}else{
echo "email not sent";
}
}

Answer 1

I did the following tasks to achieve the result.
Created a Table mail_record.
added id and mail_sent columns.
after creating the table, wrote the following code.
Connectin to database
$conn = new mysqli('localhost', 'user_id', 'password', 'databasename');
Accessing the data
$sql = "SELECT * FROM mail_record";
$query = $conn->query($sql);
$row = $query->fetch_assoc();
Accessing database to get mail_sent record.
// GETTING MAIL SENT / NOT RECORD (BLANK = NOT SENT & yes10 = Sent)
$mail_status = $row(['mail_sent']);
// CREATING THE CONDITION
if($cstt == 10 and $mail_status == ''){
// SENDING EMAIL if $cstt = 10 & email is not sent (blank)
$to = "admin#example.com, user#example.com";
$subject = "email subject";
$message ='Hi user, email text';
$headers = "MIME-Version: 1.0" . "\r\n";
$headers .= "Content-type:text/html;charset=UTF-8" . "\r\n";
$headers .= 'From: Web admin <admin#example.com>' . "\r\n";
if(mail($to,$subject,$message,$headers)){
// ADDING The RECORD THAT EMAIL HAS BEEN SENT FOR ($CSTT == 10)
$sql = "INSERT INTO `mail_record ` (`mail_sent`) VALUES ('yes10')";
if ($conn->query($sql) === TRUE) {
echo "Email sent and record added successfully.";
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
}
}
by adding a if condition / logic we can write a code to execute mail send action only once.
now if you refresh the page the first if condition will give result FALSE because $cstt == 10 TRUE but $mail_status == '' FALSE.
using this method you can be very sure that the mail will be sent only once. no matter how many times page is being refreshed.