Linkedin announces its users about the email notification system changes:
"We want to let you know about a change we will be making to some of our email notifications to make sure you get important messages as soon as possible.
Previously, due to an error on our part, your default setting was to receive a weekly summary email listing any InMails or Introductions sent to you by other LinkedIn members.
We received a lot of feedback from people saying they'd rather receive these messages right away. With that feedback in mind, we will be changing your setting on December 14, 2011 so you'll receive InMails and Introductions immediately rather than in a weekly digest format.If you'd like to receive these messages as soon as they are sent, no action is needed. However, if you'd like to change how you receive these messages in the future, you can change your email preferences by selecting the weekly digest format.
To learn more about changing your email notifications, please visit our help center.
The LinkedIn Team"