Является ли обязательным по стандарту кодирование subject-а в письмах в виде
"=?UTF-8?B?VmFsZW50aW5hIEt1cmljaGV2YSDQtA==?=" ?
Иногда я получаю письма где тема просто в какой-то кодировке как в примере ниже, является ли это допустимым с точки зрения стандарта?
Subject: ыЙОЩ ДМС чБЫЕК НБЫЙОЩ
Date: Tue, 29 Nov 2016 05:02:58 -0800
MIME-Version: 1.0
Content-Type: text/plain;
format=flowed;
charset="KOI8-R";
reply-type=original
Content-Transfer-Encoding: 8bit
В
https://en.wikipedia.org/wiki/MIME#Encoded-Word написано "Since RFC 2822, conforming message header names and values should be ASCII characters; values that contain non-ASCII data should use the MIME encoded-word syntax (RFC 2047) instead of a literal string"
в то же время как
https://tools.ietf.org/html/rfc6532 "However, fullinternationalization of electronic mail requires additional enhancements to allow the use of Unicode, including characters outside the ASCII repertoire, in mail addresses as well as direct use of Unicode in header fields like "From:", "To:", and "Subject:", without requiring the use of complex encoded-word constructs. This document specifies an enhancement to the Internet Message Format and to MIME that allows use of Unicode in mail addresses and most header field content."
Простой
