I've been thinking long and hard about this problem and I'm not sure if an email address - validated or not - is the best way to achieve the initial goals.
What are the goals of having this validated email address?
1- Inform the operator;
2- Make sure the operator will read the info;
3- Identify the operator.
I'll keep #1 for last as this is the only truly needed goal from my point of view.
Identifying the operator ID to make further decisions on how to share the traffic may be kind of useless. There are either _good_ operators and you have no real reason to divert traffic from these relays or there are _bad_ operators and they will try to hide that fact by creating multiple identities. Your validated IDs are still useless to you as identifying _bad_relay operators.
About validating an email address to make sure the operator will read the info, it is still not a guarantee that it will happen in the future. If an operator does not want to - or cannot - read his/her emails, you cannot do anything about it. Except maybe revalidating the email address regularly which is, first, annoying and, second, what are going to do if a _good_ relay operator doesn't revalidate his/her email address? Shut down all of his/her relays? You might shoot yourself in the foot going with such an attitude.
So there is no real point in validating an email. It will just turn out to be more red tape to go through.
About point #1, you want to inform the relay operator. Do you need a two-way communication method for that?
* How about putting the message to the operator on the _metrics.torproject.org_ relay page?
* Would there be any reason for the messages not to be public?
* If, somehow, a response - or an exchange - may be needed, why not put a general contact email address for answers, comments, etc. with, for example, the message ID as the subject? If the message is really personal, the message can be as simple as "Contact us at email@example.com ASAP."
* Why not put an RSS feed to be able to fetch those messages automatically and regularly?
* That way, you can also contact multiple operators based on their country, platform, etc. with the same message as well.
This would be something similar to _weather.torproject.org_ but much simpler and without a need for any kind of registration.
Are you sure all operators will follow, read, and act upon your messages? Not less than by sending an email. Much better than NOT having a valid email address at all. A _bad_ operator will be a _bad_ operator no matter what.