Customer email address rejected

I just had a customer tell me that their email address was rejected by opencart. Please advise on how to fix. The email address is formatted as follows: name@loremipsum.ndo.co.uk

you need change or remove email validation code in opencart

I would think OpenCart should accept any valid email address. Even if I had any idea how to fix this bug myself, it would require fixing again once I updated OpenCart.