Please tell me what I am doing wrong. I am sending an email using the Zend_Mail class like this:
$message = <<<STR
You have a new invoice!
Sign in to your clientarea to see it.
Best regards,
Company name
STR;
$mail = new Zend_Mail();
$mail->setBodyText($message);
$mail->setFrom('billing@company.com', 'Company.com');
$mail->addTo('client@email.com', 'Client Name');
$mail->setSubject('You have a new invoice!');
$mail->send();
It is received as a spam though. There are other applications such as Webmin on my server and emails they send is not treated as SPAM.