Tenants not picking up certified mail (lease termination)

[Joy Shaw]

Hello everyone! I just have a question on ending month to month lease. I am giving my tenants 30 day notice and letting them know that I'd like to end the lease. I sent that information via certified mail but I think the tenants are not picking up on purposes. These are not eviction notice so I'm not sure if I have to send them via certified mail? I'm just protecting myself in case we have to go to court since these tenants are difficult. I'm wondering if anyone has any experience on this type of situation. Thank you!