How to @ mention Twitter accounts
Yes you can! When you're composing a post for Twitter, start typing @ and the name of the Twitter account you'd like to mention. Matching results will be returned. Once the Tweet has been published, the @ mention will be hyperlinked.
Unfortunately tagging is not supported on other social networks through Buffer at this time. That said, if you share a post to other social networks at the same time, Buffer will convert the @ mention on other social networks to the full account name. Facebook page mentions is a feature we're currently working on and hoping to roll out pretty soon 😉