You can easily do a Google search (or on any other search engine) using certain keywords from the message received (e.g. “Thiel Meta class action”).
The website of the lawyers handling the case or the website of a firm mandated to disseminate notices to class members, such as Proactio, should be in the results of your search. You can then consult these sites for more information on the case.
It’s possible, however, that the words you’re looking for are so common that your search results won’t help you. Think of a search with the following keywords: “class action tickets”. You’ll get lots of results!
The most reliable method is to consult the Quebec registry of class actions, which is under the responsibility of the Quebec Superior Court and the law requires that notices to class members be published on the registry. There, you’ll find information and documents on all class actions filed in Quebec.