How many days old mail in phone number
I think there may be a bit of confusion here!
Mail and phone numbers are two completely different things. Mail refers to physical letters or packages sent through the postal service, while a phone number is a sequence of digits used to contact someone via phone.
As a result, it doesn't make sense to talk about the age of mail in terms of phone numbers. Phone numbers don't have an age, as they are simply a sequence of digits used for communication.
If you're asking about the age of a piece of mail, that would depend on when it was sent and when it was received. For example, if a letter was sent on January 1st and received on January 10th, it would be 9 days old.
If you could provide more context or clarify what you're trying to ask, I'd be happy to help!