It would be great if there was a way to control users being sent an message in teams when they have not been migrated yet. If we have users in Teams Only mode and they send an IM to a user who is offline in S4B, they receive an email that someone tried to message them in teams and click here to join teams. This is not the functionality we want to see happen and is killing out piloting of Teams. Users who are Skype only and haven't launch teams need to receive messages in Skype only, not teams. Teams only users need to know that message sent to users on skype will only go to users on skype and not try to have them launch Teams. This causes confusion and has caused pilot users to no longer want to use Teams in fear that the users they are trying to IM will not receive the IM in skype properly. Teams is a great replace for skype, but to get the business to buy in and pilot the product we need to make sure that they know that messages sent to users will be received in the correct tool. Islands mode is not a valid option for this as users do not want to run 2 tools. It is to confusing and complicated, considered a hassle limiting adoption for pilots users.