Allen McKenzie

I got your frustration, and you won't get any response from Zendesk... for sure...

Let me try to help you out with what I know and what I have faced before.

1. Even if you search for tomer@abc.xyz, you will sometimes get another user ( IDK why they return this user, but sometimes, you WILL get other email addresses.

So, to conclude that, make sure in your API ( or filter or whatever ) to CHECK that the email address is (lowercase) and matched into the one that the user provided to you.

(That said, it's always recommended to use lowercase as the input to Zendesk when creating new users - no matter what the customer provided)

2. you'll need another API method to get the user details when you have a match to the user email address, with this way, you will be able to grab the organization ID or whatever custom ID you created.

3. I don't know which app you're using, I can suggest MAKE.COM ( I'm not an affiliate) but I'm using it heavily on what ZD CAN'T do...
See my scenario as an example of "how-to" do it via Make (codeless site - you don't need to know Python)