Notice starts when the landlord receives it but email is not very high proof that delivery of the notice has been accomplished. If the landlord responded right away confirming receipt that would help. When you are in a situation where technicalities matter it could be a problem. Hopefully not inthis case.
The best service is personal or by certified mail. It sounds like the tenant is not in a position to deliver it personally but in cases where that is possible it is a good idea to have the landlord sign an extra copy.
