"Company sends out an email to all employees before the entry dates to notify them that it's time to enroll or change their elections. Eligibility is one year (1,000 hours) and then enter on 1/1 or 7/1 following. A key employee's wife, who is a part-time employee, was eligible for the plan as of 7/1/2020. She did not enroll in the plan. Administrator missed her in the 2020 safe harbor calculation because of her part-time status, and didn't realize she worked more than 1,000 hours in 2019. She worked 936 hours in 2020. Her date of hire was 1/7/2019. She worked 1,039 hours in 2019.

Is the email that was sent enough proof that she was notified? Or is a corrective contribution needed? They don't individually notify anyone and never have had an issue."