RBL claims I'm doing a dictionary search

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I've got this ‎RBL https://spamrl.com/  that claims my server is doing a dictionary search. I see nothing in the maillog. I have checked for an open relay using an online website. No other RBLs claim my server is an issue.‎ I am the only user that can send email from the server.  Any ideas regarding what else to check?‎