We’ve also updated our Help Center article on third-party apps and permissioning with more details.
You may receive requests to reauthorize apps affected by this change. You can always see what apps you have authorized, what they are able to do, and revoke access here: https://t.co/lxpbebEuK1
Only a small number of apps with “read/write” permissions actually sent DMs. If you authorized one of these apps, it’s possible but unlikely that they sent DMs without your knowledge. That’s no longer possible as a result of this change.
This wasn't intuitive for people, so we’re changing app permissions and improving the language to be clearer. Now, only apps you authorize with “read/write and DM” permissions can send DMs for you.
Authorizing an app can give it permission to take actions on Twitter on your behalf, like posting Tweets or sending DMs. Until today, apps with "read/write" permissions could send DMs for you (but not read or receive DMs).