All mail checker by sinus

You're referring to the "All Mail Checker" feature in Gmail, which is powered by Sinusbot, an open-source chatbot framework.

The All Mail Checker is a feature that allows you to check all your Gmail labels (or folders) for new messages at once. Here's how it works:

1. Go to your Gmail settings by clicking on the gear icon in the upper right corner of the page.
2. Click on the "Filters and Blocked Addresses" tab.
3. Click on the "Create a new filter" button.
4. In the "From" field, enter the following: is:all
5. Click on the "Create" button.

This will create a filter that checks all your labels (or folders) for new messages. You can then set up a notification or a forwarding rule to alert you when new messages are found.

Note that the All Mail Checker feature is not the same as the "All Mail" label in Gmail, which shows all your emails regardless of label or folder. The All Mail Checker is a filter that checks specific labels or folders for new messages, whereas the All Mail label is a label that shows all your emails in a single view.