imap电子邮件验证问题

Question

我正在使用蓬勃发展的lib从邮箱中获取电子邮件，我尝试从浏览器登录，工作正常。当我试图通过PHP代码登录时，它给我以下错误

Array ( [0] => a0003 NO [AUTHENTICATIONFAILED] Authentication failed. )。

<?php 
private function connect() {
        if ($this -> connection) {
            return;
        }

        fCore::startErrorCapture(E_WARNING);


        $this -> connection = fsockopen($this -> secure ? 'tls://' . $this -> host : $this -> host, $this -> port, $error_number, $error_string, $this -> timeout);
;
        foreach (fCore::stopErrorCapture('#ssl#i') as $error) {
            throw new fConnectivityException('There was an error connecting to the server. A secure connection was requested, but was not available. Try a non-secure connection instead.');
        }

        if (!$this -> connection) {
            throw new fConnectivityException('There was an error connecting to the server');
        }

        stream_set_timeout($this -> connection, $this -> timeout);

        if ($this -> type == 'imap') {

            if (!$this -> secure && extension_loaded('openssl')) {
                $response = $this -> write('CAPABILITY');

                if (preg_match('#\bstarttls\b#i', $response[0])) {

                   $this -> write('STARTTLS');
                    do {

                        if (isset($res)) {

                            sleep(0.1);
                        }
                        $res = stream_socket_enable_crypto($this -> connection, TRUE, STREAM_CRYPTO_METHOD_TLS_CLIENT);

                    } while ($res === 0);
                }
            }

            $response = $this -> write('LOGIN ' . $this -> username . ' ' . $this -> password);


            if (!$response || !preg_match('#^[^ ]+\s+OK#', $response[count($response) - 1])) {

                throw new fValidationException('The username and password provided were not accepted for the %1$s server %2$s on port %3$s', strtoupper($this -> type), $this -> host, $this -> port);
            }
            $this -> write('SELECT "INBOX"');

        } elseif ($this -> type == 'pop3') {
            $response = $this -> read(1);

            if (isset($response[0])) {
                if ($response[0][0] == '-') {
                    throw new fConnectivityException('There was an error connecting to the POP3 server %1$s on port %2$s', $this -> host, $this -> port);
                }
                preg_match('#<[^@]+@[^>]+>#', $response[0], $match);
            }

            if (!$this -> secure && extension_loaded('openssl')) {
                $response = $this -> write('STLS', 1);

                if ($response[0][0] == '+') {
                    do {
                        if (isset($res)) {
                            sleep(0.1);
                        }
                        $res = stream_socket_enable_crypto($this -> connection, TRUE, STREAM_CRYPTO_METHOD_TLS_CLIENT);
                    } while ($res === 0);
                    if ($res === FALSE) {
                        throw new fConnectivityException('Error establishing secure connection');
                    }
                }
            }

            $authenticated = FALSE;
            if (isset($match[0])) {
                $response = $this -> write('APOP ' . $this -> username . ' ' . md5($match[0] . $this -> password), 1);

                if (isset($response[0]) && $response[0][0] == '+') {
                    $authenticated = TRUE;
                }
            }

            if (!$authenticated) {
                $response = $this -> write('USER ' . $this -> username, 1);
                if ($response[0][0] == '+') {
                    $response = $this -> write('PASS ' . $this -> password, 1);

                    if (isset($response[0][0]) && $response[0][0] == '+') {
                        $authenticated = TRUE;
                    }
                }
            }

            if (!$authenticated) {
                throw new fValidationException('The username and password provided were not accepted for the %1$s server %2$s on port %3$s', strtoupper($this -> type), $this -> host, $this -> port);
            }
        }
    }

?> 

我正在使用正确的凭据。当我从其他服务器使用时，相同的代码似乎可以获取电子邮件。无法确定问题，请帮助