CB

Confirmed, issue is with the REGEX used to validate emails in the function cbIsValidEmail. It is a case sensitive REGEX.

FROM:
/[a-z0-9!#$%&'*+\\/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+\\/=?^_`{|}~-]+)*(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/@

TO: (case non-sensitive flag added)
/[a-z0-9!#$%&'*+\\/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+\\/=?^_`{|}~-]+)*(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/i@

TO: (capitals added)
/[a-zA-Z0-9!#$%&'*+\\/=?^_`{|}~-]+(?:\\.[a-zA-Z0-9!#$%&'*+\\/=?^_`{|}~-]+)*(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?/@

Also, there appears to be double escaping on periods, am not sure why so did not remove but double escaping a period is invalid as you're escaping the escape.