Agreed, it's curious! I wonder if they would still fuzz it if you changed the URL scheme to include the identifier as part of the URL path, rather than as a par

Agreed, it's curious! I wonder if they would still fuzz it if you changed the URL scheme to include the identifier as part of the URL path, rather than as a parameter? e.g., hxxp://example.com/unsubscribe/abcd1234 Please report back if you try it :-)