If you are asking how many email you can send through Powweb mail server per day, the answer would be 4800 email per day, maximum. The limit is set per hour, and current setting is 200 email per hour.
Why is this in place? To prevent user from using powweb mail server for sending large volume of spam mail.
To work around this, and use your web hosting for sending out maximum email per day. setup the email sending script to get 200 email address from mysql database. And add this script run to cron job, and set it to every hour perform once. Wahlaa.. 200 email will be sent out per hour. 
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