squirrel mail error "Connection timed out 110 Can't open SMTP stream."

error:
Connection timed out
110 Can't open SMTP stream.

=================

solution:

vi /usr/local/cpanel/base/3rdparty/squirrelmail/config/config.php

$useSendmail = false;

to:

$useSendmail = true;


restart cpanel and exim service.