Enforcing email uniqueness and addressing form login errors for existing email addresses

Overview

Certain provides the ability to prevent multiple registrations and profiles with the same email address.
The error message "A registration already exists with this email address. Please log in to your existing registration rather than creating a new registration." indicates that the email address entered by a registrant is already used by a different registration, at either the account level or the event level.
If a registrant encounters this error, verify the email address being used and verify the form settings to enforce email uniqueness within the event or within the account.
Best practice when enforcing email uniqueness is to add an entry section to your form to collect the attendee's "username and password" or their "last name and email address".
If the attendee receives "A registration already exists with this email address" error, advise them to log in using their existing email address and password.

Navigate to Plan > Forms > edit a form.
Select Registrant Details.
Scroll down to Other Options.
Review and select the appropriate email uniqueness configuration.
Do not enforce email uniqueness.
Do not enforce email uniqueness allows registrants to use any email address whether existing on another registration or not.
No error will be posted if the same email address is used in more than one registration, but it will allow for duplicate registrations.
Enforce email uniqueness within this event.
Prevents duplicate registrations within the specific event.
This will also trigger the error message if an attendee attempts to register using an email address that already exists for another registration within the event.
Enforce email uniqueness within this account.
Prevents duplicate profiles from being created with the same email address.
This will also trigger the error message if an attendee attempts to register using an email address that already exists for another profile within the account, whether for that specific event, or any other.

The best practice when enforcing email uniqueness is to add an entry section to your form to collect the attendee's username and password or their last name and email address.
If the attendee receives the "A registration already exists with this email address" error, advise them to log in using their existing email address and password.