SMTP Authentication
Zend_Mail supports the use of SMTP authentication, which
can be enabled be passing the 'auth' parameter to the configuration array in
the Zend_Mail_Transport_Smtp constructor. The available
built-in authentication methods are PLAIN, LOGIN and CRAM-MD5 which all
expect a 'username' and 'password' value in the configuration array.
Example #1 Enabling authentication within Zend_Mail_Transport_Smtp
span style="color: #ff0000;">'auth' => 'login',
'username' => 'myusername',
Note: Authentication types
The authentication type is case-insensitive but has no punctuation.
E.g. to use CRAM-MD5 you would pass 'auth' => 'crammd5' in the
Zend_Mail_Transport_Smtp constructor.