If you're not going back to work for a few days after New Year, you might not want reminders of all the unread email that's piling up to pop up constantly on your phone. Here's how to switch that display off until you're ready to get back to it.
iPhone/iPad: Select Settings > Mail, Contacts, Calendars, choose your account, and then switch the Mail option to Off. (You'll need to re-enable this to start mail syncing again.)
BlackBerry: In your Mail account, choose Options from the menu, and then Message Display and Actions. Under Display Message Count, choose None.
(For Android, whether you have an unread message count will depend on your home screen options and mail preferences, so there isn't a single catch-all fix.)