HTC desire 530 User Manual page 186

186 Calendar and Email
Some email accounts allow you to set the sync schedule. You can use Smart
Sync to save battery power. See
5. Enter a name for your email account, and then tap Finish setup.
What is Smart Sync?
Smart Sync automatically extends the sync time the longer the Mail app is inactive. Set
your email account to Smart Sync when you don't need to check new email messages
frequently. Smart Sync helps save battery power.
If you want to receive email messages as they arrive, select another Peak time sync and
Off-peak sync schedule in the email account's Sync, Send & Receive settings.
What is Smart Sync? on page 186.