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

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:

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