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UserEmail Unique ?

What is the rule for UserEmail uniqueness ? Is it unique with for the sf universe, within an org, within an org but shared with its sandbox ?

I've noticed that I cannot create a new developer instance with the same email but my email can be added to another org as an id.


The username must be unique across as a whole and the username must be in an email address format.  The Sandbox is completely separate and you can have the same username over there.  The sandbox logs in at, while all other orgs login at

On a user record, the username and email address are actually separate fields.  Therefore, if you have (for example), three Developer Edition Orgs, you could have a user account in each org (e.g., and  The username doesn't need to be a real email address, just needs to be in email address format.  For each of those users, you can put your email address in the email field.

When you sign up for a new account, it only asks for your email address and puts that in both fields.  Prior to setting up a new user in a new org, you should update the usernames of your other users so it does not conflict with your email address.

I hope that wasn't too confusing. :smileyhappy: