Why are the emails using the dedicated outbound IP addresses marked as SUSPECT/SPAM?
Dedicated Outbound IP Addresses
You will need to warm up your IP Addresses responsibly in order to maintain a Good Reputation for those IP addresses. This should be done by slowly injecting mail through those dedicated IPs with a consistent volume, starting with a low volume and gradually increasing the volume over time.
It was also strongly recommended that you ensure that SPF and DKIM authentication be configured at the time as well, as this would help with the IP warm up and reputation in general.
Please see Answer ID 2489: SPF and Sender ID considerations with Oracle Service Cloud sites where it explains that in both Sender-ID and SPF, a special TXT resource record associated with the domain name portion of an email address is queried in DNS. In the Sender-id and SPF records, you specify your email delivery policy. Neither Sender-ID nor SPF mandate what your email delivery policy is, they merely provide the tools to do so.
The receiving email servers configured to check for SPF will verify that the sending server is authorized according to the policy defined within the SPF and Sender-ID record for the sending domain name.
If your body FROM: (what you see in the email from field) domain is not an Oracle Service Cloud assigned email address, your IT department will need to publish the SPF record in your DNS. Email messages that fail SPF or Sender-ID validation are much more likely to be regarded as Junk or Spam, and handled accordingly, such as being deleted, or moved to special Junk folders.