Hello, @RBB Welcome to the forum community, that’s a great first question!
This was very recently discussed on another thread (slightly different topic)
Here is my reply on that thread:
This is from my perspective as a sitter, as there is no other way for an owner to reach out without inviting the sitter unless they have already messaged each other regarding a previous sit. But other sitters may have different thoughts and there are many great sitters on the forum who I am sure can also help 