This issue has been resolved by our email service provider's (Intercom) support team. Google is no longer flagging links to the domain chameleon.intercom-mail.com as containing malware.
Please reference to the underlying issue from Intercom for more information: https://www.intercomstatus.com/incidents/1fgmlkrmwnzd
Based on the above post from Intercom, we now consider this closed.
Once again, thank you to all who reported this issue to our team.