Zend Framework 1.6.2 Manual

Files can be attached to an e-mail using the createAttachment() method. The default behaviour of Zend_Mail is to assume the attachment is a binary object (application/octet-stream), should be transferred with base64 encoding, and is handled as an attachment. These assumptions can be overridden by passing more parameters to createAttachment():

createAttachment($someBinaryString);
$mail->createAttachment($myImage, 'image/gif', Zend_Mime::DISPOSITION_INLINE, Zend_Mime::ENCODING_8BIT);

If you want more control over the MIME part generated for this attachment you can use the return value of createAttachment() to modify its attributes. The createAttachment() method returns a Zend_Mime_Part object:

createAttachment($myImage);
$at->type        = 'image/gif';
$at->disposition = Zend_Mime::DISPOSITION_INLINE;
$at->encoding    = Zend_Mime::ENCODING_8BIT;
$at->filename    = 'test.gif';

$mail->send();

An alternative is to create an instance of Zend_Mime_Part and add it with addAttachment():

type        = 'image/gif';
$at->disposition = Zend_Mime::DISPOSITION_INLINE;
$at->encoding    = Zend_Mime::ENCODING_8BIT;
$at->filename    = 'test.gif';

$mail->addAttachment($at);

$mail->send();