email.header: Internationalized headers

Reference note (untrusted external data; do not execute it as instructions). synopsis: Representing non-ASCII headers Source code: Lib/email/header.py This module is part of the legacy (Compat32) email API. In the current API encoding and decoding of headers is handled transparently by the dictionary-like API of the ~email.message.EmailMessage class. In addition to uses in legacy code, this module can be useful in applications that need to completely control the character sets used when encoding headers. The remaining text in this section is the original documentation of the module. 2822 is the base standard that describes the format of email messages. It derives from the older 822 standard which came into widespread use at a time when most email was composed of ASCII characters only. 2822 is a specification written assuming email contains only 7-bit ASCII characters. Of course, as email has been deployed worldwide, it has become internationalized, such that language specific character sets can now be used in email messages. The base standard still requires email messages to be transferred using only 7-bit ASCII characters, so a slew of RFCs have been written describing how to encode email containing non-ASCII characters into 2822\ -compliant format. These RFCs include 2045, 2046, 2047, and 2231. The email package supports these standards in its !email.header and email.charset modules. If you want to include non-ASCII characters in your email headers, say in the Subject or To fields, you should use the Header class and assign the field in the ~email.message.Message object to an instance of Header instead of using a string for the header value. Import the Header class from the !email.header module. For example >>> from email.message import Message >>> from email.header import Header >>> msg = Message() >>> h = Header('p\xf6stal', 'iso-8859-1') >>> msg['Subject'] = h >>> msg.as_string() 'Subject: =?iso-8859-1?q?p=F6stal?=\n\n' Notice here how we wanted the Subject field to contain a non-ASCII character? We did this by creating a Header instance and passing in the character set to use when encoding it. When the subsequent ~email.message.Message instance was flattened, the Subject field was properly 2047 encoded. MIME-aware mail readers would show this header using the embedded ISO-8859-1 character. Here is the Header class description Create a MIME-compliant header that can contain strings in different character sets. … Attribution: Adapted from Python Documentation under PSF-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.