Ank on mail

I think you meant to say "bank on mail"!

If that's the case, I'm assuming you're asking about the concept of "banking" on mail, which is a common idiomatic expression.

To "bank on" something means to rely heavily on it or to have confidence that it will happen or be successful. In the context of mail, it might mean relying on a specific delivery or communication method to get something done.

For example:

• "I'm banking on this package arriving by tomorrow, so I can use the contents for my project."
• "I'm banking on the email confirmation to let me know if my application was accepted."

Is that what you meant, or would you like me to clarify anything else?