Send email not working on OJS 2.4.7.1

Hi, we’re using ojs 2.4.7.1 and send email from ojs is not working. We always got en error when send email [Wed Dec 28 08:35:05.486459 2016] [:error] [pid 13697] OJS SMTPMailer: Did not receive expected 250 or 251.

Beside an email issue, we got a report from the authors that they can’t submit their paper to reviewer. The page always back to the login page. When we check to error log we got this messages
Wed Dec 28 06:26:58.473121 2016] [:error] [pid 20258] PHP Fatal error: Call to a member function getRequest() on a non-object /public_html/plugins/generic/usageStats/UsageStatsPlugin.inc.php on line 223.
Stacktrace: \n Server info:\n OS: Linux\n PHP Version: 5.6.19\n Apache Version: Apache/2.4.18 (Fedora) OpenSSL/1.0.1k-fips PHP/5.6.19\n DB Driver: mysql\n DB server version: 10.0.23-MariaDB.

Please help

Just have the same issue also in version 2.4.7. Guess I need to leave a trace here…

Just upgraded to 2.4.8-1. The same problem still exist.
Here’s what I see on my apache errorlog file:
[Wed Dec 28 13:25:46.885191 2016] [:error] [pid 14595] [client 10.34.1.52:54792] OJS SMTPMailer: Did not receive expected 250 or 251,
[Wed Dec 28 13:25:46.885667 2016] [:error] [pid 14595] [client 10.34.1.52:54792] ojs2: There was an error sending this email. Please check your PHP error log for more information.

Hi all,

Check your SMTP configuration to ensure that it’s correct in config.inc.php.

Regards,
Alec Smecher
Public Knowledge Project Team