Setting Emailbox Quota
you can follow the below steps to set Email box Quota.
STEPS
1. Access your Plesk control panel at https://www.yourdomain.com:8443 [ Example :https://www.crmcell.com:8443 ]
2. Click on Subscriptions.
3. Click on the control panel of that subscriptions.
4. Click on Mail tab.
5. Click on E-Mail Address.
6. Choose specify new size and give the value.[Note:New value should be less than the mail box quota allocated to your reseller account]
8. Click on ok.
