If you want to send direct messages to multiple users in twitter, tweetguru is a free web tool that will help you send direct messages to followers at same time. It is very simply and easy. You can login to tweetguru via your twitter user name and password.
To send direct messages simply type twitter ids comma for separation and type your message
and finally click “Send Multi DM” button then the message will sent to followers. The message limited upto 140 words like your tweets.