Twitter just rolled out some new email notification features recently.
When someone mention/reply you, Twitter will send you an email notification. You can also set notifications when your Tweet is being marked as favorites or retweeted.

Question is, how useful is this feature? To me, I find it pointless to notify me when someone mention me. I already using Boxup to do push notification on my iPhone whenever someone mention me on Twitter. Most smartphone Twitter users also have an app that notify them when someone mention them like Twitter, Tweetdeck etc etc.
I don’t know who will find this feature useful. Seems pointless to me. Oh well. I guess it’s good to have.

Anyway, if you don’t want your mailbox to be filled with the email notification, just go to the Twitter notification settings to disable it. I’ve disabled mine before my email box get flooded.