Personally, I don't always remember to synchronize my e-mails, so an option where you can allocate a certain time period for synchronizing e-mails.
"On Login" - when you log on, it automatically begins to sync e-mails ready for the day
"Time slots" - varied time slots from 0800 - 2000 - you can schedule this to then sync within the last 10 minutes of your day.
This would be very useful