Bakini mail why wouldn't it

I think there may be a bit of a language barrier or typo going on here!

I'm assuming you meant to ask "Why wouldn't it be a bikini mail?" or perhaps "Why wouldn't it be a bikini mail?" (as in, a mail or package with a bikini inside?)

If that's the case, I'd be happy to help you with your question! However, if you meant something entirely different, please feel free to clarify and I'll do my best to assist you.