Twitter announced yesterday it is phasing in a new function sending emails to users when one of their followers adds their tweets as a favourite or retweets to their followers.

http://twitter.com/#!/twitter/status/72775840978571264

You can choose to stop Twitter emailing you about retweets and when someone favourites your tweets by going to settings > notifications

A quick straw poll of Journalism.co.uk followers found opinions are divided on Twitter’s decision to email users when someone you follow retweets or favourites one of your tweets.