New
This has been highly requested, and today we are happy to announce it's available in our message composer. Now you can send the same message to multiple apps in your dashboard in case you wanted to send a campaign across different websites/apps you own.
Start a new campaign, in the who screen select everyone, then in the top right corner you should find a button named "Send the message to multiple apps?" Click it, choose the apps you have and press send. 
