Dear member,
While submitting a letter of resignation, the resigning employee is expected to clearly mention that his notice period is for ____ days and, therefore, he will work until ____ (date). Rather than reminding the clause about the notice period in the appointment letter, if you take an undertaking from the resigning employee, then it will be fitting. While accepting the letter of resignation, you could have been a little cautious and told him to include his last working day. Therefore, even now, you may return the resignation letter and ask him to clarify the notice period.
Thanks,
Dinesh Divekar