Apparently anonymous functions cannot be serialized.
Example
$function = function () {
return "ABC";
};
serialize($function); // would throw error
From your code you are using Closure:
$callback = function () // <---------------------- Issue
{
return 'ZendMail_' . microtime(true) . '.tmp';
};
Solution 1 : Replace with a normal function
Example
function emailCallback() {
return 'ZendMail_' . microtime(true) . '.tmp';
}
$callback = "emailCallback" ;
Solution 2 : Indirect method call by array variable
If you look at http://docs.mnkras.com/libraries_23rdparty_2_zend_2_mail_2_transport_2file_8php_source.html
public function __construct($options = null)
63 {
64 if ($options instanceof Zend_Config) {
65 $options = $options->toArray();
66 } elseif (!is_array($options)) {
67 $options = array();
68 }
69
70 // Making sure we have some defaults to work with
71 if (!isset($options['path'])) {
72 $options['path'] = sys_get_temp_dir();
73 }
74 if (!isset($options['callback'])) {
75 $options['callback'] = array($this, 'defaultCallback'); <- here
76 }
77
78 $this->setOptions($options);
79 }
You can use the same approach to send the callback
$callback = array($this,"aMethodInYourClass");