SMSSender is a free and open-source Address Book plug-in exclusively available for Mac OS X 10.6. With this plug-in, users can send SMSs via BulkSMS to their contacts.
However, it's important to note that SMSSender is only compatible with Mac OS X 10.6. If you have a newer version of the operating system, you won't be able to run this plug-in.
Assuming you have the correct OS version, though, SMSSender is a useful tool for sending bulk SMS messages. It works as an Address Book plug-in, allowing you to send messages to multiple contacts all at once.
Overall, if you're a Mac user who needs to send SMS messages regularly, SMSSender is definitely worth trying out. It's simple, easy to use, and won't cost you a dime.