You may be correct about the messages being rejected from our end before they're even sent as we have multiple measures in place to prevent Spam and abuse through our network. If the embedded links are what is triggering this alert, then it indicates reported content from other recipients that is being caught in our automated filters.
To help determine what specifically is causing this and if it can be removed from our filters, you'll want to submit copy of the original message for review. I would also recommend reviewing our Bounceback Troubleshooting guide for additional suggestions to help reduce this occurrence.
CG - GoDaddy | Community Moderator 24/7 support available at x.co/247support