Sending Text-Only Emails to Specific Domain

We're experiencing a situation where a certain domain we're sending emails to seemingly has proprietary software that's causing auto opens and clicks that are skewing our email stats, among other things. (Eloqua's auto-open/proxy-open filters are not catching them.)

Our initial thoughts were to reach out to the domain owner to see if they can whitelist us/mark us as safe senders in the hopes that would stop those auto opens/clicks. But in the meantime to send this domain only, text-only emails.

I was able to use the google machine to find some directions to accomplish this. It says to access the Email Domain Rules via the Campaign management, but for the life of me I cannot find that in the interface, anywhere! Any insights would be VERY appreciated! Thanks! :)