I have installed OJS version 3.3.0.5
But no mail is being sent by system. Like registration, article submission etc.
However, I can send mail manually to the registered users.
When I try to save Email template after editing message displayed is “The form was not saved because 1 error(s) were encountered. Please correct these errors and try again.”
Probably this is because your ojs configuration is fine, but your cron is not running.
Cron is the responsible of doing scheduled tasks… like the ones you mention.
If is the case, your ojs won’t be able to show updates in your statistics.
There are different ways to enable cron, but fastest/easiest is enable the Acron plugin.