Hello @Bushell23,

Welcome to the Klaviyo Community! 

In order to restrict your sign-up form to only accept emails containing specific domains, you’ll want to build a custom/legacy signup form via HTML. Going the custom route would allow you to full control of how the form is designed and behaves - including restricting who can submit. 

Alternatively, if you wish to use a Klaviyo built sign-up form, I would recommend either embedding the form on a hidden landing page that only staff have access to or by using conditional/trigger splits or flow filters to target just your staff members when issuing the discount code. You can even take this a step further and link the form to a specific list. 

I’ve actually seen this done successfully using both a hidden landing page and a trigger split in the flow that issues the discount code. Essentially, even if a non-staff member somehow found or got their hands on the URL for the hidden page to fill out the form, the trigger split in the flow will direct users down two separate interactions based on what their email is. If they’re a staff user, they would go down the normal experience where they receive a discount code. 

If it’s identified that the subscriber is not a staff member, they’ll have found an Easter egg congratulating them and celebrating them for their efforts. You could even include a smaller discount in this email to persuade the subscriber to purchase and promote your brand. 

I would just recommend excluding these list subscribers from your campaigns, as they may not be the best users to reach out to considering they are primarily staff members and ones who found the Easter egg.

I hope this helps!

David