I need to send Twitter messages to groups and if I do will the tweets be private and not re-tweet-able?
I don't know if this adds any value to the answers already given, but I think it boils down to a matter of perspective about what Twitter is. You are seemingly attempting to use it like an email list, but it is more like a radio station... you broadcast, people tune in.– aserwinSep 27, 2012 at 15:36
As of now short answer no. A possible solution would be to create another twitter account. Protect the updates and have the people you want to communicate follow that account. As far as retweeting... I believe this is always possible. Even with protected updates.
Alternative would be to send a bunch of direct messages.
Might need to choose a different medium for communication if this is necessary. Such as email.
While you can protect your tweets so that only those you approve of can receive them, there is nothing you can do to stop those same people re-tweeting you.
Yes, it's right there in the settings under Tweet Privacy:
☐ Protect my tweets
Only let people whom I approve follow my tweets.
If this is checked, your future tweets will not be available publicly. Tweets posted previously may still be publicly visible in some places.