Messages are usually composed from words, not from random letters, so you don't need to bruteforce all letter combinations. Also, some messages use a template,

Messages are usually composed from words, not from random letters, so you don't need to bruteforce all letter combinations. Also, some messages use a template, for example, a message from an online store like "Your order number XXXXX is ready for pickup" or a message from a bank saying "Your PIN code is XXXX". In this case, all you need to guess is a number.