We’re cleaning up your contact list so that Messenger contacts who don’t have a Skype account no longer show up in your Skype contact list.
Any Messenger contacts who do have a Skype account will remain in your contact list, so you can still reach them on Skype. Plus, Messenger contacts that are removed from Skype will continue to be available as email contacts in your People application at www.live.com.
Note: When sending a message in an existing conversation with a Messenger contact, you may see your message stuck in "Sending" state or receive an error "Delivery failed". To ensure your messages are delivered, find the person in your contact list (not your recent conversations) and start a new conversation with that person.