mail order noun
plural ∼ -ders 1 [noncount] : a method of buying products that are received by mail
▪ You can purchase the books by mail order. 2 [count] : a product that is sent by mail to the person who bought it
▪ The store sent out all its mail orders in time for the holiday.
▪ You can purchase the books by mail order.
▪ The store sent out all its mail orders in time for the holiday.
— mail–or·der 
/ˈmeɪlˌoɚdɚ/ adjective always used before a noun
▪ a mail-order catalog [=a catalog of products that can be ordered through the mail]
/ˈmeɪlˌoɚdɚ/ adjective always used before a noun ▪ a mail-order catalog [=a catalog of products that can be ordered through the mail]
