In the event that you're interested, I -may- have uncovered why ALL of the email problems are occurring...
The notifications are configured to be sent from <admin@www3.camaro5.com> but they are actually arriving via www4.camaro5.com. Additionally, while there are DMARC records for the various domains (camaro5.com, camaro6.com, etc.) there are no records for the actual domain listed in the emails: www3.camaro5.com.
Since there is no record present, every receiving email system gets to choose what to do with unverified emails by default. Gmail and Yahoo! seem to be configured to be much more strict and completely discard them while Hotmail (and likely other MS-based domains like outlook.com) are allowing them in but FORCING them to the Junk Folder and not allowing users to override that handling.
For the couple of minutes it takes to add a DMARC record for www3.camaro5.com, it might be worth testing.