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Invalid links during a Newsletter sending test
If you do a test send of your Newsletter (last step before the final send)
then it is normal for the links present in your sent message during the test (top part: "READ THIS EMAIL IN MY BROWSER" = link to see the message in a browser and bottom part: "UNSUBSCRIBE" = link to allow the user to unsubscribe) to not work.
They will of course be functional when you actually send the newsletter.