Scheduled Annual Maintenance - Infrastructure upgrade in our Data Center - Dec 23rd to Dec 28th, 2015

Scheduled Annual Maintenance - Infrastructure upgrade in our Data Center - Dec 23rd to Dec 28th, 2015

During the Scheduled Annual Maintenance - Infrastructure upgrade in our Data Center - Dec 23rd to Dec 28th, 2015, mail can be accessed or we will have to wait till 28 to avail zoho email services ?

Thanks