Chances are that your emails and other forms of contact traffic to exchanges will be marked as spam. I am quite sure that exchanges are being bombarded with emails where people try to sell them domains, 'whale insider information', bug information, information about competitors, etc. People are desperate to earn money and will try to get it where possible.

Best odds of succeeding (even though they realistically speaking are very low overall) is to get in touch with brand new exchanges that are trying to start up and attract users. Don't waste your time trying to reach out to the Coinbases of this world.