The term BY MAIL can be broken down into two crossword solutions: POSTAL (6 letters) and MAIL (4 letters). POSTAL refers to the postal service, which is a system of delivering MAIL and parcels from one place to another. The postal service has been around for centuries and is still used today to send letters, packages, and other items. MAIL is a term used to refer to any type of communication sent through the postal service, such as letters, postcards, and packages. By MAIL is a phrase used to indicate that something is being sent through the postal service.