In the context, you are using the letter 'u' as though it might be a word in and of itself. It is a letter not a word. Since you are clearly mentally equipped to handle operating a computer in some capacity to even find the internet, there is no excuse for mistaking a letter for a word nor for you to even think of using it in that capacity. You have the full keyboard in front of you[unless you're doing something odd like using a gaming console to do so] so you might as well use the entire thing so people with whom you're communicating with in text format do not assume you are a complete derfwad. tl;dr u is not a word. It is a letter.
They are not worth your time, Laurence. Reading the signature should tell you not to bother with this one.