[tor-relays] Problem with sendmail on relay

Good morning, I've setup my first relay. Until now everything seems to be working fine, but I keep getting mails from logcheck I don't know how to deal with. The reported errors are: "sm-mta[15148]: STARTTLS=client, relay=smtpin.rzone.de., version=TLSv1/SSLv3, verify=FAIL, cipher=ECDHE-RSA-AES256-GCM-SHA384, bits=256/256". Thank you for any hints! Best wishes Berta