Don't forget to turn on sync when you add new folders or Mail Categories
While the settings to enable and change sync settings for Gmail haven't changed in the latest update, many people are just being introduced to them for the first time with the addition of "Mail Categories" this last week. Simply enabling the new Mail Categories feature on the web view of Gmail will get the tabs to show up in your app, but unfortunately won't start syncing or notifying you of your mail to those categories by default. It'll take just a few taps through the settings of the Gmail app to have everything syncing and ringing once again though, so let's take a look at the process.
While in the list view of the folder or tab that you want to sync and notify, hit the "Menu" button and tap "Label settings". Here you'll see sync and notification settings specific to that folder you were in, as noted in the top left area of the action bar. Tapping the top "Sync messages" area, you can select between not syncing, syncing the last 30 days (by default) or syncing all messages that arrive in that folder. Select one of the latter two to get email downloaded automatically when it hits that folder of your account.
Once email is syncing automatically, you can then choose how you would like to be notified of emails that arrive to that specific folder as well. You can wholesale turn notifications on or off, change the sound, choose whether or not the phone should vibrate and whether it should notify for every message or just periodically. Because you can change this option for every folder (or Mail Category tab) in your account, you can granularly control how your phone responds to email based on how you've categorized its importance of notification. Using this in conjunction with the new Mail Categories feature could greatly cut down on the amount of distractions you receive from unwanted email.
Take a look below where we give a quick video look at managing sync and notification settings in the new Gmail interface.