My dating website (iloveyou.dating) didn't come with this feature - an automatic welcome message to the onsite inbox / received messages, so it's very useful. It works as it's described. The only thing that is missing is the multilingual capability - which would be nice. If someone signs up using French site language, then he / she would receive the welcome message in his / her own language.
This is one of my favorite plugins, I have 9 plugins from Purusothaman Ramanujam so far. This is the perfect way to not only greet all of my new members but to also give them information that they need on how to do certain things on my site.