Get-ADUser by email ignore case

Hi,

I try to update AD user information. The unique identifier is email address. How can I get-aduser by email address but ignore case?

The email addresses from the source file are upper cases, like "YONG.CHEN@COMPANY.COM", the email address in AD is like "Yong.Chen@company.com". I don't want to assume the case in email addresses will always be consistent.  How can I get-aduser by email but ignore case?

Thanks,

Yong