Why Headers Preventing mail from sending? - php

Question

This might sound similar like previously asked questions but trust me it's not
I Was trying to send an email that uses an HTML template via PHP mail() function from Localhost and a Hostinger Server but they created different problems.
On localhost the email was being sent as plain text although there were headers
$headers =
"MIME-Version: 1.0\r\n" .
"Content-Type: text/html; charset=UTF-8";
I have gone through all the similar questions in stackoverflow and tried each and every thing but I couldn't make it work. After some more research on this I found out this
I assume, that your email client is considering the smtp-server "unsafe", and hence is just going to display all the html as plaintext, rather than rendering it
Therefore I switched over my hosting and tried to do the same but this time I found that the headers are causing the problem. The email is not sent if the header variable is passed in the mail() function. I tried to concatenate the headers which didn't worked. Then I made an array of headers and joined them with php implode which too didn't worked. On a similar question on stackoverflow I found that webmails mess up if html, head, body tags are used as they use xhtml. I removed them and still no success.
I tried error reporting too and it showed module sqlite3 already loaded which I think is not related to mail.
Below is my code
php
<?php
$email_template = file_get_contents("path/to/my/template");
$lucky_number = rand(999999, 111111);
$email_template = str_replace("{{user}}", "User", $email_template);
$email_template = str_replace("{{lucky_number}}", $lucky_number, $email_template);
$sender = "from:iusername#host.com"; // I found that if I dont use from, my mail ends up in spam folder
$receiver = "username#host.com";
$subject = "Random Subject Name";
$headers =
"MIME-Version: 1.0\r\n" .
"Content-Type: text/html; charset=UTF-8";
if(mail($receiver, $subject, $email_template, $sender, $headers))
{
echo "Email Sent Successfully";
}
else
{
echo "Email Sending Failed";
}
P.S I can't use PHPMailer or other similar libraries

Answer 1

The sender information should be inside the headers
Hence, please change the following lines:
$headers =
"MIME-Version: 1.0\r\n" .
"Content-Type: text/html; charset=UTF-8";
if(mail($receiver, $subject, $email_template, $sender, $headers))
to
$sender = "iusername#host.com";
$headers = "From: $sender <$sender>\r\nReply-To: $sender\r\n";
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-Type: text/html; charset=utf-8\r\n";
if(mail($receiver, $subject, $email_template, $headers))