First, add your admin userid to the config file.
open ./includes/config.php
around line 129 you will find
PHP Code:
$config['SpecialUsers']['canrunqueries'] = '';
add your userid. if its '1' then it will resemble this
PHP Code:
$config['SpecialUsers']['canrunqueries'] = '1';
save/re-upload the file
Go To
AdminCP->Maintenance->Execute SQL Query->
Select
Code:
Yes - Send Notification Email When a Private Message is Received
under All Users
Click "Continue", and then on the next page click "Continue" again to "Confirm Query Execution"
Done.
And so you don't have to keep doing it, set it to do this by default by going to
AdminCP->Settings->Options->User Registration Options->
Check the box in the "Default Registration Options" section that reads
Code:
Send Notification Email When a Private Message is Received
Save. Done.