That opens the discussion as to what one defines as written. Does it mean pen to paper/typed up and printed with the one party delivering the physical paper to the other? If it was on a post-it note would it be acceptable? Is electronic correspondence considered written as there is typing involved? Text messaging is electronic and there is some form of typing involved but it's very informal and how do you show it in court (not tv court but traditional court) if push came to shove and you needed to? I don't think to save my text messages and I sure can't print them out. I imagine you can take a screen shot if you have a smartphone of some type and print out that picture. However, I don't use texting as a form of communication with my tenants. In business, deals and arrangements are often discussed via email and text but in the end a physical contract or notice is drawn up and signed to make it clear and official.
There are a lot of questions that require examination of previous cases and rulings involving text messaging and their standing as legal written notice. That form of communication, originally was designed as just for short and quick messaging while you weren't able to make a call for whatever reason. A short "I am on my way", "stuck in traffic," "what do you want to eat for dinner." Within the last couple of years, people have entire relationships solely via texts. Everything from the mundane and silly to serious life changing discussions are happening via text and the law hasn't really caught up enough to firmly and cleary factor this into legal matters that we face everyday.