Salesforce has recently updated to Winter ’11 and one of the defaults is a daily email of your Salesforce Chatter posts and feeds. If you would like to stop receiving this email, or if you would like to receive it weekly instead of daily, please follow the steps below:
Log into Salesforce and select your name up top in the blue header. Select setup and then under Personal setup, select My Chatter Settings and then Chatter Email Settings.
Here you can turn on or off all emails, decide what will trigger an email and set the frequency of your digest emails. The “Help for this Page” link at the top right will have more information on this subject.