Zend Mail is declared as Ratware - zend-mail

Question

I'm using Zend_mail with SMTP in a wrapper class like this:
//$_config has all required and valid attributes to send a mail successfully.
$tmpconfig = Array('auth' => 'login',
'username' => $this->_config->MAIL_LOGIN,
'password' => $this->_config->MAIL_PASSWORT);
$this->_transport = new Zend_Mail_Transport_Smtp($this->_config->MAIL_SMTP,$tmpconfig);
$this->_mail = new Zend_Mail();
$this->_mail->setFrom($this->_config->MAIL_ADDRESS, $this->_config->MAIL_SENDER_NAME);
...
//$_data has already all required and valid fields and values...
$this->_mail->setBodyText($this->_data['maildata']['BodyText'],'UTF-8','UTF-8');
$this->_mail->setSubject($this->_data['maildata']['Subject']);
$this->_mail->addTo($this->_data['maildata']['RecipientEmail'], $this->_data['maildata']['RecipientName']);
$this->_mail->send($this->_transport);
Scenario 1: I'm sending the Mail with a test account to a proprietary server to a test mailaddress from my testsystem. This mail will be received.
Scenario 2: I'm sending the Mail with another test account to another proprietary server to the same mailaddress, with two test systems. This mail is rejected as ratware. I've already talked to the server administrator, he said that the mail generation is incorrect. There is no valid EHLO greeting: "remote host used our name in HELO/EHLO greeting."
I don't really know if its a problem within the zend_mail class or the test systems.
1st Testsystem: PHP Version 5.3.2-1ubuntu4.14, Apache/2.2.14 (Ubuntu)
2nd Testsystem: PHP Version 5.3.1, Apache/2.2.14 (Unix) (Apache on Mac OS X)

Answer 1

I think your 2nd mail server is configured too strictly, or perhaps it's a problem with how you're configuring Zend_Mail. Zend_Mail works great for me, and I'm using it to send emails to multiple SMTP servers, including the ones at Gmail and also at a popular shared web hosting service.
If you're sending on port 25, I believe many mail servers are more likely to treat your message as Spam. Does your 2nd mail server support sending with alternate ports? Typical alternatives are 465 or 587. Also, have you tried sending via SSL or TLS? These might also help convince that server that your messages are legitimate.