Questions about - delivering a lease non-renewal letter

[Rema W.]

I'm self-managing a property, as an out-of-town landlord. I have some relator "boots" on the ground that I can engage with on an ad-hoc basis if needed. 

But I'm wondering if I can handle this myself. 

I have a tenant whose fixed-term lease ended 8.31.2021. I'm not renewing.  I'm giving them 30 days as a courtesy.  Their last day is 10.13.2021. In Louisana, per law, I only have to give them 10 days notice to vacate. 

I've sent an email, called, and texted the same, letting them know the above.

Questions: 

Should I deliver a non-renewal lease letter? Does it need to be posted on their door? 

Can I mail it? If I mail it is it valid? 

What does a non-renewal lease letter do?