Hello Brandon Mackean,
If the SNDS access request is being sent to "trusted" email addresses that you cannot access, there is unfortunately no alternate approval path available to bypass the ownership verification process. SNDS grants access based on the ownership or management information associated with the IP address, and the authorization emails are sent to contacts that Microsoft associates with that IP range.
If the IP is owned by your hosting provider or their upstream IP provider, only they can approve the request or update the ownership/contact information used for verification. RDNS, domain ownership, or being the customer using the IP is generally not sufficient to change the authorization contacts shown by SNDS.
In this situation, your best option is to continue working with the actual IP owner and ask them either to approve the SNDS request on your behalf or to remove and re-establish the IP assignment using contact information they control. If they are unable or unwilling to do so, Microsoft does not currently provide a manual approval process that bypasses the trusted-email verification mechanism.
If you believe the IP ownership information itself is incorrect, gather the IP details and ownership documentation and contact Microsoft Sender Support to determine whether the registration data can be reviewed, but access approval will still require verification tied to the IP owner's records.
Harry.