Hello, I found this in the deliverability report:
Failed: Symantec Messaging Gateway (formerly Brightmail) Business-to-Business
Failed some message filters:
[Caution: Message was marked as a Spam due to content containing suspicious URL content.
Symantec Messaging Gateway service combines advanced email antivirus, antispam, and content filtering capabilities in an easy to manage solution. This can either be a hosted solution or a virtual appliance
How to find what URLs are considered suspicious?