PHP mail causing phishing warning on gmail - php

Question

I am using PHPMailer to send automated e-mails from my website and while testing, I noticed that when I sent mail from website by Gmail, then e-mails sent by php mailer are generating the following warning on the recipients end:
This message may not have been sent by: example#gmail.com Learn more Report phishing.
But when I use other emails (like yahoo, outlook), then I got no emails in my $contact_email. Please help me to solve this problem.
PHP Mailer code:
<?php
global $_REQUEST;
$response = array('error'=>'');
$user_name = substr($_REQUEST['user_name'], 0, 20);
$user_email = substr($_REQUEST['user_email'], 0, 40);
$user_msg = $_REQUEST['user_msg'];
$contact_email = 'contact.arefin#gmail.com';
if (trim($contact_email)!='') {
$subj = 'Message from Official Website';
$msg = "Name: $user_name
E-mail: $user_email
Message: $user_msg";
$head = "Content-Type: text/plain; charset=\"utf-8\"\n"
. "X-Mailer: PHP/" . phpversion() . "\n"
. "Reply-To: $user_email\n"
. "To: $contact_email\n"
. "From: $user_email\n";
if (!#mail($contact_email, $subj, $msg, $head)) {
$response['error'] = 'Error send message!';
}
} else
$response['error'] = 'Error send message!';
echo json_encode($response);
die();
?>

Answer 1

When you send bulk emails and especially when you mock the sender address, you need to use best practices that may reduce how many servers block you as spammer.
Three things which I think you should do are:
1) Use appropriate mail headers
Add the following to your code - a notice that this is a bulk sender, and the OPT-OUT email address:
.= "X-mailer: YOUR_SITE_DOMAIN Server" . "\r\n"; // this will identify the real sender
.= "Precedence: bulk" . "\r\n"; // this will say it is bulk sender
.= "List-Unsubscribe:info#YOUR_SITE_DOMAIN\r\n"; // this will reveal the OPT-OUT address
Read more about it here
2) Make sure your server domain has a reverse DNS record. This will tell the recipient's server that your domain is REALLY hosted on your server.
3) Publish SPF record with your domain. You can read more about it here, and google it for other big handlers (like Yahoo).
In addition to those, make sure you are adding a footer with a "one click" OPT-OUT removal option and explanation note that this message is sent on behalf, and who is the original sender.
Cheers

Answer 2

You can either set up google apps for your site and get a Username#yourwebsite.com gmail account (more info: http://www.google.com/enterprise/apps/business/), or You will need to set up an e-mail address on your current server that is Username#yourwebsite.com and use that as the $mail->from address.
Your E-Mail recipients are receiving the message because you are telling google to send an e-mail from your server, and then you are telling them that the mail is coming from gmail, which it isn't, it's coming from your personal server. Since the from address and your server address don't match, they flag it as spam. This is googles way of preventing spam, to them it would be the same if you put $mail->from(YOURMOM#LOL.com). The e-mail would still send, but your domain name does not match the # address.

Answer 3

Try this code , In your code i found some mistake which i have solved here.
global $_REQUEST;
$response = array('error'=>'');
$user_name = substr($_REQUEST['user_name'], 0, 20);
$user_email = substr($_REQUEST['user_email'], 0, 40);
$user_msg = $_REQUEST['user_msg'];
$contact_email = 'contact.arefin#gmail.com';
if (trim($contact_email)!='') {
$subj = 'Message from Official Website';
$msg = "Name: $user_name
E-mail: $user_email
Message: $user_msg";
$head = "Content-Type: text/plain; charset=\"utf-8\"\n"
. "X-Mailer: PHP/" . phpversion() . "\n"
. "Reply-To: $user_email\n"
. "To: $contact_email\n"
. "From: $user_email\n";
if (!#mail($contact_email, $subj, $msg, $head)) {
$response['error'] = 'Error send message!';
}else{
$response['error'] = 'success!';
}
} else {
$response['error'] = 'Error send message!';
}
echo json_encode($response); die();