I send an email to my customers with a receipt. I am using my server to send this email from my business email @gmail.com and it contains a link to the receipt image on my server. However, gmail labels it as possibly phishing, specifically that it is not from my business email address. What can I do to stop it from claiming it as phishing?
<?php
$mifb = $_GET["mifb"]; //link to the receipt pic on my server
$tpppp = $_GET["tpppp"]; //customer email
$fyppp = $_GET["fyppp"]; //my business email @gmail.com
$headers = 'MIME-Version: 1.0' . "\r\n";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
$headers .= 'To: <'. $tpppp.'>' . "\r\n";
$headers .= 'From: <'. $fyppp.'>' . "\r\n";
$message = '<!DOCTYPE html><html><body><a href="http://www.mybusinesswebsite.com"><img src= '.$mifb.'></a>The receipt is in an image format</body></html>';
mail($tpppp, 'For Customer George Walters', $message, $headers);
?>
You have to use SMTP for proper sending your email via gmail. Here is how: https://stackoverflow.com/a/2748837/4362168
Alternative try to use services like mandrill, postmark or amazon ses It's pretty simple to setup, and they will guide you through the process o setting proper spf and dkim records for your domain so emails you send will be more trustworthy.