I put in a case and here's the response I got.
Greetings,
Thank you for contacting Cisco Meraki Technical Support!
Cisco Talos is reporting this domain as neutral so this may be a false positive.
https://talosintelligence.com
Surprisingly, I've seen this across thousands of MX's and you're the first customer has asked about it. That said, I'm going to reach out to our vendor who manages these categories to to report this as being a false positive. The vendor name is BrightCloud and I will let you know once I hear back from them.
https://www.brightcloud.com/tools/url-ip-lookup.php
If you have any questions or additional clarification is needed, please let me know and I'll be happy to help.
Regards,
Casey Keller
Cisco Meraki Technical Support
Like I indicated, I got the "its the first I've heard of this being reported". I'll post more once the case gets updated.