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App for Slack: FAQs
No, Slack does not allow us to automatically update the preview image. Plus will show you the latest version at the time the message was sent. In public channels, you can click on Resend latest version which will fetch the latest version of the Snapshot or Page and send a new message in the same channel. You can also set up a recurring subscription for Snapshots.
The Plus app looks for URLs of Snapshots and Pages where the link sharing permission is set to "Anyone with the link can see this." If share link is not enabled, you will receive a message in Slack that prompts you to update the permission setting.
Anyone in your workspace will see the preview images, even if they don't have a Plus account. In order to access other options (like refreshing the Snapshot in Plus or creating a subscription), they will need to install the app and connect their Plus account.