The unwanted – or no longer wanted – content will be removed for everyone in the conversation in real time, but pay attention: unsend doesn’t work with friends who are still using the old version of Yahoo Messenger. This soon won’t be too much of a problem, anyway, as Yahoo will no longer support the legacy platform as of August 5, 2016.

So, if you’re still using it, don’t forget to update in advance. Read more at http://www.forbes.com/sites/federicoguerrini/2016/07/28/revamped-yahoo-messenger-lands-on-windows-and-mac/#adf441c75f43